These actuator are crap, they don't even fit, Polm on the forum bought one, was a pain.
Alright, if I were you here's what I would do:
1. Isolate the turbo pressure monitoring system from the vacuum system of the car, which mean, get a boost controller and block the VSV, so you have a closed loop between the turbo inlet housing and the actuator (Note this will cancel the boost by gear function and you will have consistent boost on all gear)
2. If that didn't work, lubricate and test the actuator system, use an air compressor @ around 15-20psi (max is 30 I believe) and try to make the actuator , actuate (haha). If it does move but you can clearly hear a whistle or air coming out of the actuator case, then your diaphragm is toasted, you'll need another actuator.
3. Port the wastegate exhaust, use a Dremel carbide bit, ideally you would want the exhaust housing separated from the turbo since metal flakes will go in the exhaust housing and on the impeller, which isn't ideal.