Electric Window Help

[partybish]

Hi guys,

My drivers' side electric window on my phase 3 HDI doesn't work.  So far I have:

checked the fuse
swapped out the relay
unscrewed the door pin connector, cleaned the points on both sides with WD40 and a brush (they seemed fine anyway)
cut the cable tie on the door connector, removed the rubber housing and checked the wires (they all seem intact)
replaced the window motor mechanism for a brand new one
swapped the passenger window switch to the drivers' side (this didn't work)

Work noting that the driver's side window switch doesn't seem to work the passenger window but it does still work the electric mirror.

After changing the window mechanisms in both doors my passenger side window now works just fine. 

I'm wondering if the next step is taking the dash out or whether I have missed something really simple.  I'm not sure how I check if there is power coming from the door connector - I tried using a mains tester electric screwdriver on the pins but it doesn't light up - I haven't got a clue if it should however. 

Any help you can give me to help diagnose the fault is much appreciated. 

Cheers,
Matt