I have recently replaced all bearings,seals in pgi gearbox,intially it seemed to be quieter than before but there are some noises.Lower gears theres a slight whine as you go faster theres a bit of a groan type noise at about 30 mph at approx 50 mph it gets worse,in gear out of gear,no throttle dos'nt to seem to make any differance.Correct oil grade used,any ideas