Brake servo Mk2

I have a couple of original Mk2 servos that I can strip and inspect, they may be toast! if so what is available? I understand repair kits are available for the fluid side but maybe not for the air side? I have seen servos offered as 5-1, what is the boost ratio for the original?

You can get new aftermarket servos from main vendors. I prefer SNG Barratt… I rebuilt the servo in my 420 and the kit had hydraulic seals and the vacuum diaphragm.