Thanks Matthew. I have: cleaned out the caliper, replaced the piston seal, replaced the top hose with stainless steel (and am waiting for the delivery of a new bottom hose), and cleaned and rebuilt the m/c. When I refilled, the m/c took a very long time to prime and sent the fluid down very slowly. Now, after about 90 minutes of bleeding over several days, the lever is still very spongy and under pressure I get a fairly constant stream of tiny bubbles in the reservoir. Could the m/c be sucking in air somewhere? I've now taken it apart and rebuilt it twice. Incidentally, there was no check valve in David Silver's new kit, as shown on the Haynes exploded diagram, but I gather this is normal as the part is unnecessary...? In addition the piston and secondary cup that came with the kit were very slightly different to the ones that came off the bike (although the same length and diameter) so I simply cleaned up and re-used the old ones. In truth I suspect the whole arrangement needs to be looked at by someone who knows more about it than I do...!
