Those wastegate cracks shouldnt keep your turbo from making boost unless the wastegate isnt closing at all. Our TT k03 had these cracks (well I even guess all turbo's that have over 200.000km) and happily spooled to 22psi. Would blow itself into bits without wastegate control. Have you done a pressure test on the inlet side? And hows the compressor doing, is it in good shape?

Take off the first silicone connector that is fitted to the compressor outlet of your turbo. Plug it with a 2" O.D. cap with a connector for pressurized air (I have made a very simple version with just a car tire-valve). Take off your oil filler cap and apply pressurized air to the tire valve (or connector) untill you reach your boost pressure (I would want to see at least 20psi), then go and listen for air leaks around the engine. You can also have this done at a garage, where they will usually include smoke into the system so leaks get visible. If your system can hold 20psi with only gargling from the valve cover, your turbo is the problem. If not, repair and test again.

Good news, you could not have replaced the actuator without removing the turbo anyway 

I was just going to say check the actuator arms you can generally attach a hand pump and observe / adjust normally.

Also check Id of hoses and their wear.

Gets got though after a few runs so mark ur original spot!

There will be threads all over on this on Google (wg Check)