Thanks for asking around. The pots have recently been cleaned, and twisting some of the dials while the static is present doesn't seem to make a difference. Perhaps there is a failing solder point or something, maybe I'll pull it from the rack and poke around.
I have a pair of MX-4 crossovers that I like very much. At power-on, one of the two outputs a fairly low level static that sounds like crinkling plastic for about 20 seconds before it goes away. After that, the static is gone and the crossover sounds like it is functioning normally. If the crossover is on for a length of time, then turned off and back on again, the static sometimes reappears. This only happens in one of the two crossovers. Any ideas on the cause?