thanks for all the input, everyone. spit-balling replacement parts puts me at about 80 GBP before shipping on the amal website (which doesn't include slides+bores). as rewarding as i think it may be to rebuild them, i think the time i would spend on that fight is worth the rest of the balance for a replacement pair (particularly considering there's no guarantee they'd work terribly well at the end of all that time, money, and self-flagellation).