How to unstick "frozen" rear brake on 2011 R1200RT?

[SAWCoach]

My bike has been in a dry garage for 13 months.  A pre-ride inspection revealed no braking action at the rear.  I suspect that the calipers, etc may be frozen on place. Is there a way to check this before disassembling the entire brake?  Any easy ways to unfreeze the thing?  Thanks.

[Our Gee]

Very easy job to remove the Caliper and free off the pistons. A combination of thumb pressure to push them inwards or a G Type clamp if they are really tight should work. Normal break lever pressure should then be enough to push them outwards then the piston surfaces can be carefully cleaned. Keep an eye on the Fluid level in the reservoir as it will increase as the pistons are pushed in.

[SAWCoach]

Thanks