I've refitted my brake servo to my car (Calibra c20xe, 1993).
Now I've had the engine out, did a rebuild and put it all back in agasin, the brake servo is my std one, so I know it worked before. I connected the brake pedal up to the fork on the servo, filled up the brake resouvour and started to bleed the brakes. All 4 calipers are now done, but the brake pedal still feels soft, not spongey, but just goes to the floor easily. There is alittle bit of resitance half way down, but then its dead easy to press in agasin.
The other tale tell sign is that its noisy when your pressing the brake pedal, like a squeeling sound. I presume its air coming out of the servo. Exactly where is the 'air' or vacum seal on the brake servo? According to hayes there is no seal or gasket to replace, just bolt on the master cylinder (2 nuts).
I managed to fire up the car, I only have a few gears working but when moving forward and pressing the brakes...well it was a bit fritening, they were crap.....reminded me of the days when I used to drive my Nova SR