I've been searching the forums but I can't seem to narrow my problem down. My Kubota is jumpy moving - going forward and backward. It's not the 3-point hitch or the lift - those are smooth. Mine occurs for just a few seconds after changing from forward to reverse (or vice-versa). It 'bucks' a few times, and then smooths out. Local tractor mechanic said the clutch is good, (but he also said a part that I needed replaced was not available anywhere, and I found it in 10 minutes online). Any ideas what would cause this?