Piper headliner (was: simple and cheap tricks for your plane)

We have a Cherokee 140. I want to know if anybody knows the simple
and cheap trick to clean our headliner. It is actually in fine
condition, but it has a LOT of brownish spotting on it, apparently
caused by moisture (you know, condensation, leakage, etc. - not
that OUR plane leaks!). It looks like crap. The headliner appears
to be a heavy fabric, almost seems like it is vinyl coated.

I tried washing it, spraying it with a variety of liquids (ammonia,
bleach and water, Formula 409). They helped to reduce the intensity
of the spots by about 30%, which is not nearly enough.

Ideas?

Tim Long
CMA, CA