You can order a manual from JD at 1-800-522-7448.
Have your credit card handy. ~$16.00 total.
this info was on another yesterday tractor post.
if its still current it might be the best info I can give you.
buy the manual and set down and read it cover to cover, it should tell you how to set up the bar angle and knifes for best result.
does you tractor have an rpm meter, so you can tell your pto speed and ground speed?
as others have said, you need to know this info, so when you find your mower sweet operating spot. you can go back to that speed and rpm time and time again.
I have an old MF cycle mower and they can be Cantankerous at best in heavy hay.
just look around today and see how much heavy hay is being cut by cycle mowers verse the new type spinner mowers.
they will cut through most anything and the speed control is just as fast as the operator can stay on the tractor.
good luck with the old mower,
note to file: !!!!!!!!!! be so careful when you raise and lower the bar, remember the blade can slide up/down when you do this and you must, must, must have your fingers back out of the way!!!!!!!!!!!!