The NH 570 and 575 balers can have difficulty delivering good bale shape in some very dry conditions with long stalked material.
What is it you are baling, at what moisture content, and approximate relative humidity (at ground level)?
There you are 3 questions in one!
The string has no effective metering, just sufficient tension applied equally to the two strings to stop them unrolling and making a mess. The fact that one string is longer than the other is because one side of the bale is packed more than the other.
You have mentioned the plunger to knotter timing, and the feeder fork timing.
I am not clear of the timing you are referring to. Is it the right rotor to left rotor and left rotor to packer fork timing, or packer fork to plunger timing ?
The 575 has a pickup designed to slip. If the belt driving the pickup does not slip, the baler may be over feeding which is a cause of misshapen bales. Overfeeding delivers too much hay to the right side (cut side) of the bale. The right string is longer and the bale is banana shape with the middle of the right side bellied out.Here is a previous post on this issue
Posted 30 July 2014 - 09:29 AM
"I have had problems with banana baleson a NH 570 and tried many solutions.
But first check that you are not overfeeding the machine, overfeeding causes the bale to be overpacked on the right side (knife side). One cause of overfeeding is driving too fast. Another and the most common is lack of slippage on the pickup drive belt.
The pulley sheaves on the belt drive need to be shiny. New machines have paint in the sheaves and older machines can have rust there. Even after 35,000 bales there was a full coat of paint in the sheaves on my 570.
Ease the spring tension on the belt drive idler pulley (left side of machine) until the belt can slip. Instructions on the correct torque are in the manual but here goes

.
The 575 is designed to have slippage in the pickup rotation when under load with hay. Look on the left side of the baler (left and right is determined by standing behind the baler)
Before doing any thing carefully watch the smoothness of the pickup with the baler being turned by hand and listen for any components making contact that should not be, the most common is fingers on the guards.
On the left side there is a vee belt in a sheave behind the toothed cog that drives the knotters, and that goes down to another sheave that drives a shaft that crosses over to the right side of the baler.
There is an idler pulley riding behind the vee belt and tensioned by a spring (adjustable).
The pulley sheaves must be clear of rust and paint.
This belt is designed to slip to prevent overfeeding of hay up the pickup. Overfeeding will result in banana bales with too much material in the right side of the bale (cut side) and too little in the left side.
THe correct adjustment is between 15foot lbs and 20 foot lbs at the pickup, but 20 may be a little high.
How do you set this?
Put a bar (edge up) under the centre shaft of the pickup, (a flat bar will fit between the pickup guards) and over the top of one of the bars that the pickup fingers are on and under the centre shaft of the pickup.
Measure carefully from the centre bar out along the flat bar a distance of 34 inches. The best trick is to put a small notch in the edge of the flat bar so when it slips under the pickup centre shaft it locks into position, and you can thus have the 34 inch mark in place and similarly notched.
Put the hook of a spring balance in the 34 inch notch and get your trusty helper to turn the baler by hand. The belt should slip ie the pickup not rotate with the spring balance reading at least 53 lbs and no more than 69lbs.
Adjust spring tension on the idler pulley accordingly to bring the point of slippage into this range.
If there is not enough adjustment then make an extension link to add between the hook on the end of the spring and the idler pulley. I could not get slippage to polish the paint out without that extension and then had to tighten up the spring once the sheaves were polished metal.
The next thing to check is the packer fork setting. To pack more material in the left side, set the packer fork connecting rod in a lower hole of the packer fork. Moving this mounting point down packs more material in the left of the bale. If still not enough move the connecting rod to the right at the anchor point.
New Holland suggested adding another set of holes to the rear and 50% phased to the top of the packer fork, the effect of which is to lay the packer fork further back.This was fitted to another baler with success, see Youtube
This seems to be a fix for not enough material in the right side of the bale . it did not work for me as the problem for me was not enough on the left side.
REMEMBER that the timing of packer fork to plunger Must be checked whenever the anchor/connection points are changed.
As a further modification I added another rotor teardrop on the rotor shaft immediately before the packer fork, such that this shaft then carried three teardrops. The extra teardrop was added to the rear of the shaft with a woodruff key installation the same as the original. The reason I did this was to provide extra support to the volume of hay being moved by this rotor, there being about 9 inches of material behind the standard rotor teardrop There is room to clear the rear of the bodywork and the packer fork.
This helped more than any other modification, including the left hand feeder wedge and the long/ short grass hay wedge"
NH provided the same solution to me as that shown on the YouTube clip but it was no help at all.
The packer fork has 9 possible settings and is the next set of adjustments after the pickup slip is adjusted to correct banana shape. The aim is to pack more hay into the left side and less into the right/cut side. There are 3 hole sets in the packer fork and 3 sets on the anchor point.
Whenever the packer fork throw is adjusted, check the packer fork to plunger timing to make sure the forks still clear the plunger. Turn the baler by hand and watch the packer fork/plunger clearance.
To increase the amount of hay packed into the left side of the chamber, place the pin in the lowest of the 3 holes in the packer fork. this pushes the packer fork further into the chamber and thus more hay to the left. This seems counter intuitive because the first thought is to adjust the packer fok the other way to reach further back and grab more hay. The local NH techs tried this and the bales exploded on coming out of the chute the shape was so bad.
If there is still insufficient hay in the left, place the anchor pin to the right hole in the set of holes mounted on the baler, the hole set closest the centre of the baler.
Failing that there are two optional wedges to fit in the pickup area. Strangely in an early handbook one of the wedges is described as a "long grass wedge" and in later editions as a "short grass wedge". If you are not confused I sure am.
The best of these is the left hand hay wedge a wedge shape in the floor of the transfer area just to the left of the left rotor, the action of which is to lift the hay a little higher for the packer forks to grab.
In exceptional circumstances referred to above the rotors and packer fork break a truck in the hay and will not pack enough to the left side. My understanding is that Arkansas has a hot but humid climate so excessive dry down should not be an issue. However with extreme hot, dry conditions I found that an extra rotor arm on the left rotor set helped reduce banana shape. That addition takes some setting up and machining of a woodruff keyway.