RE: Tamiya KV-2 Gearbox
Is it the gear in your 3rd and 4th photos? It looks as if the plastic gear hub cracked? Can't be certain from your photos as they aren't
clear or illuminated well. If the hub isn't cracked I'd run a small pin through the plastic gear, brass piece and shaft to keep them
all together.
I know they're less expensive for Tamiya to use but this is why I don't like plastic gears in such an application; especially
cheaper inexpensive injection molded gears.
An alternative, don't know it it would be appropriate, is to put a proper sized washer on the shaft next to the gear that wants
to go awol then use a small collar next to the washer to keep the gear from moving but keeping it captive against the brass piece.
Jerry