Update on my 222 - I have oiled, fiddled, replaced the needle, and it stitches! I am so relieved that I don't have to try and adjust the timing, cos I couldn't get out a crucial screw. Now I don't feel as if I bought a pup any more.
I would still like to get a new screw for my needleplate sometime - I'd be happy to buy or swap for fabric or something if anyone has one. Thanks for putting up with my rambling.