Idler Gear Bearing

Well after a little close listening, I suspected the idler gear bearing (13H7848  I.D.(shaft diameter) .750", O.D.-1.063"., equivalent to the SCH1212) was a source of some of the whining sound generated while the motor is under load.

Pulling off the gear cover and examining the gear, the pins looked OK but all on-line guidance indicated replacing it should help.   There are two identical bearings, one in the block and one in the cover.  The gears all look OK so there are only a few things that could cause the whine.  

Removing the bearing from the block was easy but the one in the cover took heating the cover with a heat gun to 75C and then strong repeated pulls with a slide-hammer + blind bearing puller rented from my local auto supply.  The new bearings installed easily.  This did allow me to check the end-float on the idler bearing and it measured with feelers at 0.004 inches.  Right in the desired range.  Everything spins easily and upon reassembly, the whole motor sounds quieter though the whine still exists under load.

This tear-down project did permit some additional cable clean-up, a lowering of the controller and the replacement of a piece of sheet metal along the side of the engine compartment.  This now simplifies motor access.

After some additional research, I replaced the oil with 20w50w given the age of the gearbox and the fact it never operates at a temperature above ambient.