Tom_Russell
Guest
I also have a 525 head but havent had any problems with it.  Quick, look for a piece of wood to knock on!  Can you turn the head easily through the entire cycle by pulling on the beltIJ  A couple of years ago I tightened the hold down clips and had to go back and loosen some because I couldnt turn the head by hand.    I assume you have made sure everything is tight in the sickle head mounting area.  I hope someone else has better answers.  Good luck and let us know what you find.  Tom in MN