Do this...
https://m.youtube.com/watch?v=FNz00OTRLzM
put a spanner or bock of wood between the moving calipers so you can force out the stuck pistons, then clean and grease as per the video. That should sort it. I'd guess your seals are not in too bad a state if the other pistons are moving.
https://m.youtube.com/watch?v=FNz00OTRLzM
put a spanner or bock of wood between the moving calipers so you can force out the stuck pistons, then clean and grease as per the video. That should sort it. I'd guess your seals are not in too bad a state if the other pistons are moving.
-suck-squeeze-bang-blow-