Dear Everyone,
Thank you for your replies.
Bob, I'm not sure I can post photos to this site, or if I can I'm not sure how. The rating plate is a bit scratched, but I can read the following:
Wright Electric Motors (Halifax) Ltd., No. A51637, HP 1, Volts 220/230, Phase 1, ~50, RPM 2800, AMPS 7.[1?], Rating Cont, COS [zero with a slash through it (sorry, don't know that alphabet), then illegible], Halifax England
It's not a sealed motor, so you can sort of see in the open ports at the top.
It's struggling to start, so when the shaft would normally start to spin after switching on, it makes kind of a buzzing noise, the shaft remains stationary momentarily and then it slowly starts to spin. Once it gets going it seems fine and has full power. There was no no smoke or bad smell. I can spin the shaft by hand very easily, but it doesn't seem to help if I start the shaft spinning by hand (just so it's not stationary) and then switch it on--even then it still struggles. This problem started quite suddenly and got progressively worse over three or four uses of the machine.
Paul