The cymbals and hihat have never been loud enough, rather, they've been much quieter than the rest of the voices.
Today I searched through the archives at yahoo groups, and discovered that this is a well known problem that has a known fix. After replacing three resistors, the cymbals are much louder :)
However - the stupid silent hihat is back. Earlier this year I had problems with the hihat not triggering (or not making any sound at least). When I put a probe from my oscilloscope to either the collector of Q73 or pin 2 of U42, it worked, but when removing the probe it stopped working again. Somehow I managed to make it stay working, but now it is broken again. No idea why, this really frustrates me!
Also, the main output is way too low and the main output pot is working the wrong way, turning DOWN the sound when moving to the right. Strange.