Combines Bad vibration on a 1020 header

Have suffered from a similar problem, and to some extent we still do although not quite as bad as your problem. I would check the PTO shafts that run the knife drive, our splines were worn which was causing a significant part of the problem. Hope this helps meanwhile I will keep thinking of what else we did. Because it is VERY annoying. We have to replace those bushes in the support arm annually and rebuild the splines annually. The spline that attaches the PTO to the shaft on the front has been replaced with a boltable type to eliminate any movement. Get back to me with any more queries.

Mo_rice, Our knife head was barely hitting the third or fourth guard (first standard guard on left side)at full right stroke. Grind it like the left three or four "head guards" to give clearance. Also check the left PTO tumble bar. Some enginering genius decided to put 90degrees of free play between the yoke assembly and the hex coupler to aid when hooking up the PTO. This will hammer apart in a season. Hope it helps .

I once had a 25' 1020 head with a bad vibration which was caused by a hairline crack right in front and to the right of the wobble box, which was not visible until the sickle was running. If the head has done any contour farming, this is the first place they break.