12" Wallstreet display contrast?

I've just finishing fixing up a rather badly abused 12" passive-matrix cacheless 233mhz Wallstreet, for no good reason other than I wanted to see how well it would run Jaguar. The problem is that the display works fine unless OS X blanks it. When it comes back, the contrast is set really high, so it's almost white. The brightness buttons work, but the contrast buttons seem to be mapped to the volume, and I can't find any way of resetting the contrast other than a reboot.

Anyone got any ideas on this?

Incidentally, it runs Jaguar better than I thought, though it is probably helped by having 256mb RAM.

Thanks!