just a few things to check make sure slip spline on drive shaft is free disconnect drive shaft and fan,elevatorandheader drive belt turn gearbox by hand check for any drag good luck!!!
The splines are free and the pulley can be turn by hand. That gearbox was re-bearing with the right gap by the dealer 800 hours ago, and its still due now, but the gears are nice and shine. Thanks lex.
Yes it was put apart 800 hours ago for re-bearing prevention by the dealer. Today the gears are nice and shiny but the bearing are slightly spotted so that exclude a bent shaft i guess. One more thing, still some moisture in that gearbox even after adding that extra vent. I think it comes from condensation for that heat. Thanks lex.