0-6-0 Loco wheels seizing

[Gvndual]

I bought a used Bachmann 0-6-0 Switcher and tender. It won't run because the wheels keep seizing up. I have it almost completely disassembled, but I can't get to the gears, which is where the Hangup seems to be. Any advice? And unfortunately I can't get an image small enough or in the right format to attach.