87 5KCSTQ instrumentation light problem

["Paul Meyers" <paulm@viewsoft.com>]

The lights controlled by the instrumentation booster module are
intermittent. The condition is easy to demonstrate, even in the daylight by
the AC control module going black when the headlights are turned on. I have
been able to reproduce this by dangling the booster from its cable harness
while driving and, after a warm-up of, say, 10 minutes, having an assistant
give it a sharp rap. Poof, out go the lights.

Audi wants almost $300 for a new part. I was able to secure another part
from my local auto wrecker, but, after about a week, it has begun to exhibit
the same problem. I have not yet done the dangle/rap test on it, but I am
dismayed that perhaps many of the parts of this vintage have the same
problem. I have heard that broken solder traces are endemic on older Audis.
Is there hope of finding a good used module, or do I just need to (gulp)
learn to live with the problem? Is there possibly a way to get a circuit
diagram of this part, so I could trouble shoot it myself?

Paul Meyers 87 5KCSTQ 130K miles