On30 Shay disassembly

[RickyRail]

Does anyone know or have the proper disassembly instructions for the 2 truck On30 Shay? I have been troubleshooting the loco. The DCC sounds are good but no noise or movement in the gears. The loco seemed to be getting warm and then today does not move. In testing the diodes, D1 & D2 on the main board, they appear to be open. Has anyone ever had the problem of burning out these diodes before? The rest of the circuit checks okay. I just want to test the motor before changing the diodes to make sure the gear train is free.
Thanks for any interest or help.
PS... my truck gears are all good, no splits.