I am currently putting all new brakes on my kombi and decided on a new booster as well as the pedal slowly fades at certain times but no fluid leaks, as i was replacing everything i noticed the new booster is not the same and wont bolt up so after my annoyance subsided i decided to have a closer look at my booster and started to unpick the original press joins to have a look inside.

The problem with mine is there was a buildup of rust inside at the seams due to a previous fluid leak i assume, the rubber diaphram look ok so i started cleaning up the rust inside and re etch primed it, the centre piece was actually bare metal never primed so i put a coat on it as well, i will take more pics when back together.

the below tool is what i used to pry it appart after i used a chisel to separate the joins a little

Your pry tool looks like an old falcon or chrysler hubcap removal tool, i used a couple of these in the workshop for grease cap removal and various other jobs.
If the pedal sinks slowly it is usually a leak past the cups in the master cylinder which will explain no fluid loss,a booster vacuum leak will give a rock hard pedal as there is little or no assistance. Cheers Les

yeah what he said about the rock hard brakes and the sinking pedal being stuffed piston seals in the MC

oh well, at least my booster is rust free and clean inside again

All back together again, bolted it back up last night

my 2 yr old son was nice enough to lose the pin which joins the booster to the pedal