Turbo/Dump valve question

[skuda]

I have a suspect standard Dump Valve on standard turbo. If you apply vacuum to valve nothing happens so the diaphragm is suspect.
1.Can these be replaced? I've heard you can get OEM diaphragms, anyone know where?
2. I know it's tight on the 225 but can you remove the Dump valve as is or must you take turbo pff?
3. If you have to take turbo off it looks a nightmare?

Eventually removed the dump valve/recirculation valve, took awhile undoing the bottom bolt. Valve slid out easily, checked rubber diaphragm for holes/splits, aok. if you press down on diaphragm against the spring(which is on the other side of rubber) and put your finger over the inlet pipe, then this creates a vacuum which holds the diaphragm against the spring till you release your finger, cleaned everything and re-fitted valve backon.tested vacuum by using a vacuum gauge/tool, held vacuum no leaks.
Back to my original problem, overboost. Boost solenoid changed prior to above, will try the new solenoid again.