I have a couple of ancient 870 motors (the 4.5v ones) that run but don't sound great. I've looked for, but can't find, a guide on how to dismantle them. I'd like to either get in there and clean/lubricate them selectively, or perhaps even replace the motor element.

The end cap where power is supplied is clearly where they went together, but some gentle wiggling and pulling suggests there's probably some internal one-time assembly clips.

Is there a trick to get them apart?