95 vitara brake problem

[200sxdon]

Need some help with this ,
just put my girl friends vitara back on the road to use as a daily for a while so i can do a underbody refurb on the 200,
it has been sitting for three years so changed disks and pads and new flexi front pipes ,

i also changed the master for a brand new one as it was leaking.

But the brakes keep locking up on me so i called out the aa who said it was sticking pistons, so i brought some refurbed cailpers
but it is still locking the brakes ,

i spoke to a mate who said undo the master and pull it forward a few mil off the servo air escaped and the brakes released and it started to roll so is it the servo at fault or something else

[ANDY black s13]

It should have a one-way valve in the vacume source from the inlet to the servo,it could be sticking/knackered
Or the new/2nd hand master cylinder push-rod length is adjusted wrong,too long possibly so can't release? no pedal replay?
needs 3/5mm between pedal stop and applying the brake as see that BMC was swapped
All I can think of atm its too early

[200sxdon]

It should have a one-way valve in the vacume source from the inlet to the servo,it could be sticking/knackered
Or the new/2nd hand master cylinder push-rod length is adjusted wrong,too long possibly so can't release? no pedal replay?
needs 3/5mm between pedal stop and applying the brake as see that BMC was swapped
All I can think of atm its too early

Thanks Andy ,when I fitted the new master could'nt see any ajustment on it the servo is still the original and all the ajustment is on that so will have a play with that

[200sxdon]

Any thing else I can try?