I recently obtained a free curbside KR 570 in great cosmetic condition. This is my first synth, but not first diy project. After disassembly, I find that 81 out of 88 hammers are cracked, with two in pieces, and several more on the way. As it is hard completely close cracks by squeezing together, it appears that this plastic shrinks after a couple of decades, and then cracks easily. I tried Loctite gel superglue on one hammer with cracks and it flowed in and between the lead weights and plastic overlay in some areas suggesting this might be adequate. It looks like a decade ago, one could get a complete set from Roland for about $300, but nowadays, it seems like the going rate is more like $1,000 for parts of unknown age on eBay. Since this was a free instrument, I don’t mind less than perfect repairs, if they hold up for a couple of years while I get acquainted.
Does anyone know what plastic is used - high density polyethylene, polypropylene, nylon Kel F, etc?
Does anyone know what glue is optimal?
Has anyone tried cutting a jig out of wood to fit around the hammer top and bottom edges to hold things in the correct orientation while clamping while glueing?
The felts are quite depressed for the keys in the center of the keyboard. I have ordered the 1129 felts for the key stops, but the lift and hammer felts are currently out of stock.
Has anyone had success with using a razor blade to carefully remove a felt and then shift it right or left to bring the unused surface in position? Would Scotch double-stick tape work to re-seat or would contact cement be better?
The previous owner said it worked fine except for the broken hammer keys, so I am expecting the electronics to be OK, with perhaps an issue or two with dirty potentiometers that I might be able to restore with Deoxit.
Or should I just harvest spare parts, junk the rest, and buy a new keyboard?