My works van is a 55 plate pug expert with 75k miles on the clock. Our fitter recently replaced the brake pads but since then the servo assistance has become erratic. He says he forced the pistons back with some difficulty, when I've had that problem with pistons that don't require screwing back in I've bled fluid off at the nipple.
A quick google suggested that the master cylinder seal lip coul become damaged by doing this.
The symptoms point to failed servo but I cannot see how this would get damaged and wonder about the coincidence with the pad change.
There is a good suck from the pump. The brake works normally on first push but then the pedal pushes back and if pumped again the brake feels hard and with little retarding effect, much like after a stall when vacuum is lost.
After playing with it a while I found with the footbrake applied and the engine stopped there was no noticeable movement of the pedal as the engine started.
I thing replacing the servo is an engine out job so to be avoided if unnecessary.
Any other thoughts?
AJH