ok ill give it a shot , so if the shaft is bent its no good and where can i pick up a nother shaft?????
I tilled about 150 feet with mine, turned around tilled back, raised it, started back down the garden and it shook so hard that the generator housing and the carburetor mounts both broke! Bought another 990 AND (PAY ATTENTION) ORDERED A NEW DRIVE SHAFT from some ag company, it is square shaft, not round, tried to till, shook just as bad as the old shaft, broke the tiller mast where it mounts to gearbox.
I have had the drive shaft straighten at a machine shop and have come to the conclusion that shafts made for 540 pto's will not work at 2500 to 3600 rmp.
Like TD&D said "Make sure the shaft is bent and it's not the input shaft on the gearbox or the PTO shaft on the tractor that's bent." I think the first 990 in my case has a wore out jack shaft that contributed to the problem .
I have give up on mine for two reasons, MF135 with 5 foot tiller and I really want a Case Hydra drive tiller! It is more fun tilling on a Case 646, the MF135 is just work!