Makes perfect sense. Thanks for the concise explanation - I appreciate it's a bit of a repeat of info you've already given out earlier in the thread, which I should have checked back on...sorry!

Anyway, it does give me cause for concern, since although my motor appeared to at least work (i.e. turn manually without any obvious impediment + spin seemingly ok when in circuit with supply switched on) there must clearly have been a too-high current draw which originally blew the thermal fuse and later (via long-term use of speed setting 4 as the only available option) the switch contacts.

So I am filled with a sense of impending doom which has taken the shine off my small ebay price triumph

I've alreayd WD40'd the top bearings of the motor - i.e. the ones that are immediately accessible. But to be thorough, I might try to prize the motor assembly open (following something someone else posted earlier mentioning rubber lugs that can be pressed in)...to see if I can get some WD40 onto the bottom bearing. Feel free to reassure me the whole thing's not going to fall apart if I do press those rubber lugs in!