There are two or three on eBay at the moment. If you buy one with worn, hooked teeth, they can have the worn teeth machined off and new dentures fitted. Alan Noakes has done this for me a couple of times but he is not taking on any more work at the moment as he is doing jobs on his house. If a sprocket is loose on the hub spigot it can be sleeved and machined back to a nice easy fit. I have assumed that you have an Enfield type rear cush-drive hub/sprocket assembly. The other type fitted in 1929 was the Webb, and these are easier as the sprocket is just a flat plate type, and a sprocket ‘blank’ can easily be fitted. I’ve sent an article on the subject to our Yowl Editors a couple of days ago, and I still have a couple of sets of new 2018 stock cush rubbers in stock, at £12-00 per set, plus £3-50 for UK P&P. PM me if you need a set.