I'm glad you got there in the end as I had run out of ideas.
I was going to say lock of the brake lines and drop the calliper is some sort of penetrating fluid.
I think as the rubber gaiters have gone this allowing for rust to get to the callipers and any period of letting the car stand for a while will cause rust to get to the piston walls and cause you problem.
I'm glad you stuck in there as you saved your self quite a few $$$$'s
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OEM RS4 Body| RS4 front Brakes| RS4 shocks & H&R Race springs| RS4 Xenons| 18" BBS RC wheels| Scroll K04 Outlaw|RaceTec FMIC| Southbend StageIII clutch| Autobahn88 Silicon hoses| Baileys DV| Waiting to be fitted: TT MAF| 380 injectors| RS4 Rear brakes & a Remap
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