Proportioning valve disassembly issues

[ESP47]

I'm rebuilding an original prop valve and I can't seem to get the piston on the left and the small piston in the middle of the picture out. I've soaked both for a couple days in PB blaster to no avail. I've banged it on a wooden table. Blasted air into it while banging it on the table. Even made a flared brake line that I connected my compressor to so I cold ensure it's getting a full blast of air and that didn't work. The inside didn't seem terribly corroded but those pistons just will not come out. Does anyone have any advice on any other methods or chemicals I could try that will loosen up the pistons without killing the brass?

 

[Dana67Dart]

It's likely that the seals have glued themselves to the walls of the cyl

The earlier non proportioning valve type have a hole straight through so after you remove a tube seat you can use a rod to push the pistons out.

 

[jos51700]

Block all the holes but one. Hook remaining hole to master cylinder. Pump pump pump it out.

 

[CFD244]

Make up some fittings and use a grease gun......That's how I got my K/H pistons out.

 

[ESP47]

Thanks for the replies. I was able to get the big piston on the left out with the master cylinder method but the small piston in the middle is still stuck. I'll keep trying.