I have a 250x that had been sitting for sometime. I noticed that it was very hard to push around. I pulled the rear caliper off and the piston is stuck in the housing. Anyway to free these up. Would like some advise before I go tearing into it.

 

Which way is it stuck? It wont go in, or it wont come out?
If it wont go in, back off the parking brake adjuster, so the piston can go in.
If it wont come out....brake fluid in resivouir? Tried pumping the brake lever with the calipher out of bracket, and does it come out then?
Will the brake pedal get firm? or does it travel too far?

 

The piston wont come out, let me re-phrase that. It will with my help. It wont with the pressure of the brake fluid. Was real rusty. Sides of the piston dont look to bad though.