Defective Xenon Control Unit: Causes & Fixes

Hello!

Has anyone perhaps looked into the issue of defective xenon control units in the Sharan / Golf etc. in more detail?
They tend to fail relatively often, and they're not exactly cheap, costing around 300€ when new.


In my case, one of my headlights isn't working, and it's due to the control unit for the automatic headlight range adjustment (aLWR) located on the back of the headlight (part number 7M3 907 391 or 1 307 329 068), and not due to a faulty internal igniter.


Which component could be defective, and which one is the controller for the diagnostics?
Can this chip be easily removed and soldered into otherwise identical xenon control units from BMW or Mercedes-Benz, so that the aLWR also works with these?

Here are two pictures of the STG circuit board.
http://golfsinnig.de/bilder/foren/xenon1.JPG (rear)
http://golfsinnig.de/bilder/foren/xenon2.JPG (front)


Sure, here's the translation:

"Thx."
Michael.