The wastegate operates through pressure. The boost pressure in the intake side pressurizes the lines which put pressure to the wastegate solenoid which activates the wastegate. If you can pull the hose going to the wastegate and can put 12-15 psi into it you should see the wastegate moving.

Try opening the hood and checking for cracked hoses and open connections. IT sounds like there is a leak on the pressurized side. You might try opening the hood and having someone blip the throttle and rapidly rev the engine up to 4,000, then back down to idle. If there is an air leak you might hear it while the engine is winding up under boost or when the engine is under vaccum and slowing down. It's worth a try.
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Nathan Valles, Black 855R, MBC, tint, strut brace, RE 730's