Definitely lube the pins after cleaning them up. I'd replace them if they are pitted or scored. In a pinch, you can source cheap replacement pins for a MINI at your local parts store (Autozone, etc.)
I've seen a few where the pads are really worn out and the piston is all the way out, that makes it harder to re-engage the threads. The only way to overcome that is just to push really hard while turning the piston, until the threads re-engage.
If that isn't your issue (the piston turns freely but doesn't screw in) and you're having trouble with the tool binding? (piston turns freely then locks) then you have to release the nut on the inside of the tool a bit as you screw the piston back in.
If the piston just doesn't turn it could be corrosion in the caliper, in which case you need new ones.
The pads were really shot, I got one the side to screw in, This side turns and turns but doesn't seem to engage the threads. I had to take a break and ask. Guess I'll just push harder.
Thanks Dave, I went back out and bingo, it screwed right in.
Have you found your lower guide pins get really tight? I have the bronze ones, it seems dry but it's awful tight, so was the other side. Only the lower one.
I had one of my guide pins flare out at the side where the allen wrench
went in, making it a very tight fit in the Tyrol brass guides. I had a hard
time getting it out, in fact, and when I replaced it with a new pin, it was
perfectly fine.
I think the lesson is: don't overtighten the pins.
They might have siezed....
I know the time I forced them in, it was very hard on one side...about 30-50% through the next set of pads, it was toast....siezed fulley...keep your eyes not for a spare IMO. You will likely need it.
