Brakes-Left front/secondary master cylinder 5thGen

New to VFRWorld. Just did serious rebuild at 56k miles on my 1998. I upgraded with galfer SS lines, ebc pads, new front rotors-All bearings and bushings in front-wheels/forks. I get great pedal, but left front caliper/piston for the linked brakes is loose/floppy-move by hand then when braking, from 31-15mph it 'bounces' and gives a discomforting feeling and sound. Hit a sharp bump and it bounces. My Honda tech is 'good' (13 years), has bled this system six ways to Sunday, good pedal the whole time. Tried to get factory tech to look but of course its got 'aftermarket' on it. There was another VFR in the shop (hit by a deer on side) but the front end was OK, that left caliper was tight, couldn't move it. Any ideas would be helpful, Thanks