Another tech question for ya.

On my right, front brake, there is some rubbing. I pulled off the tire and brake pads; it turns out that only one caliper/piston is in motion initially. The bottom caliper moves and the top stays still. When the bottom caliper extends to a certain point, the top caliper engages but at a slower rate. Eventually both calipers extend fully.

I thought there might be air in the line, so I bled the brakes, but that didn't seem to fix it. i thought maybe a bad crossover brake line, but then wouldn't both of the calipers engage slowly? maybe just a bad caliper?

If that's the problem, can you rebuild calipers or do you just buy a new one?

t.i.a.