rear disk caliper not retracting

[Emond Ling]

If anyone has experienced this problem of the rear piston NOT retracting,
please advise.

Last night I was swapping a set of rear brake pads on the P10 [looks
similar in style to the B13 BTW] with the same parking brake mechanism.
The driver side rear piston rotated [counterclockwise] in to the caliper
successfully, BUT the pass. side one retracted a bit then just quit
retracting, I can still turn the piston but I get no retracting, the
brake fluid reservoir cap is off. Maybe the old fluid is really clogging
the lines, I will try to bleed all the lines tonight. Could the parking
brake possibly affecting the piston to not retract on only the pass side?
Options? Maybe the piston seal needs to be rebuilt? There are no tears of
rips on the piston seal boot, anyone have the procedure to rebuild the
caliper?

BTW anyone know where to get the special tool with 4 "keys" that fit over
the piston?

Thanks,
Emond [on digest]

91 SE-R T28 turbo
94 G20T bone stock