BAsically you need to test if its retaining vacuum afer your switch the engine off.

So run the engine briefly and then switch off, and either pull the pipe out of the servo (could be tight) and if theres pressure you will hear it, or pump the pedal and it will progressively get hard as you use all the vacuum up.

Servo repair kits.......LOL.......not a chance! If only

£120(ish)+ VAT from Ford