130 XE -- Intermittent sound and Excess Flux

I have a 130XE that seems to to have a short or a break somewhere.  If I press pretty much anywhere on the mobo I can make the sound come and go. I've gone over the bottom of the board with a good light and magnifying glass.  Nothing looks remotely suspicious.  Any suggestions other than "touching up" all the solder joints?

But there is a lot of flux on this board, and that might be masking a solder problem.  What can I use to remove the excess flux?

Thanks,
Larry