8404
Gold Member
I would find a safe way to view the to stump jumpers to see if they have any unusual wobble to them at low RPMs. If one shakes or wobles more than the other then its will be clear which one of the two migh be damaged. the stump jumper itself wont be the problem it would be the output shaft that spins the jumbers, and sometimes when one of the gear boxes get worn or damaged they will have a intermitant vibration at differant RPMs too.