hi there i noticed , whilst movin the mighty beemer (not tina) around that the rear brake was binding .So took it of and serviced it, this is how
first remove caliper
remove all detachable parts , pads , clips,retaining pins etc .....and clean
in this pic i have blown one of the pistons out using a track pump .
remove the seal and bushing ..... and clean the seals and the grooves they live in .
Clean also the piston
lube the seal housings and piston with brake fluid and push back into the hole it came out of.
once both pistons are serviced ,reassemble and err put it back on the bike!!
err good luck and if you f**k it up dont come runnin too me cos your brakes dont work
next week valve clearance ......