Servo Advice?

The Servo on my 1997 Defender 90 is offering little assistance(if any) to the braking. Tested it by pumping the braking pedal, then starting the engine, which did not alter the pressure. All the pipes appear in order. Has anybody any idea whether the whole servo needs replacing, or can they be repaired in situ?
Many Thanks

The servo was replaced on our my 1997 110 last year for the same reason. Cause was obvious though, there was a corroded hole on the servo housing...

If that's not obvious I guess it's worth checking the rest of the system for leaks before diving in with a replacement. Others will be far better than me to advise on what to look for though.

Nice to have brakes again!

you will have to decide whether theres a vacuum to servo or servo leaking ,just replace if is

I think the servo test is:

Engine off... pump brake pedal and hold down... start engine... good servo = pedal drops, as the vacuum is applied.

My servo went - corroded/crack... had a few scarey moments, as the first braking (slowing down) was good, then second attempt (to stop) nothing!!

Servo is not a serviceable part to had to be replaced... gaffer tape over the crack provided a temporary solution to limp home...