Help Please..... rear brake caliper piston won't compress

[Jed_S]

I could sure use some help with a modification I'm trying to finish. I removed the rear wheel so that I could change out rims - silver to black. When I try to compress the rear brake caliper piston to put the caliper back on the bike I cannot get it to compress at all it just won't budge. I have tried using the parking brake lever to turn it manually but that doesn't work. I used a C clamp to try to compress it and that doesn't work either. It seems like it's locked out for some reason. As you can see from the attached picture I've extended the piston a little bit too far trying to wiggle it back and forth to make sure it would move at all. It moves out just fine.

I don't want to remove the brake line because I figure I'll have to bleed the brakes and reading the manual that sounds like quite a chore and it sounds like you need BUDS also.

Does anyone have any tricks they know of or can give me any guidance on this?

If I remove the brake line will I have to bleed the brakes for sure?

Any help would be greatly appreciated.

Thank you,

Jed