I'm looking at buying a set of Shimano XT brakes on Craigslist, model BR-M765 from a 2005 bike, but the guy selling them says there is a problem with the rear brake: "The rear brake barely moves the caliper piston. It acts like it needs to be bled, but I tried that and it seems to be well bled. I'm not really sure where the problem lies." Does this ring a bell with anybody? He wants $45 for both of them, so I figure even if it is a big problem I'll still get a good front brake for cheap.