NH 268 baler issue

When baling last year two different tractors ( ford 4600 and a tractor with over 100 hp) made almost like a chirping noise when bailing. If you keep the windrow light or slow down there are no noises. Bales great. I observed that the pto shaft looked to bow and then the noise. I put a new pto shaft on it just got done baling using my ford 4600 and it will still make the tractor make all kinds on noises when the hay is thick. Otherwise the baler does what it is supposed to.

Does any body have any ideas on what I should try looking for or replacing?

Thanks,
Matt

NH 268 baler issue