So it sounds like what you're saying is you have a hum that developed, not one that resulted as a change in setup. If that's the case than your right to suspect the crossover. After all its almost 2014 and you bought the crossover in 95 used so the caps are in the 20+ year range. Its also a good time to get at the inside and just give things a general once over (clean connections, pots, terminals etc).
Recapping is easy if you feel confident with a soldering iron I'd go for it. Two recommendations I have for you that will help is make sure you got a good soldering iron with the right sized tip and preferably temperature control. If you have a tip that is to large it will be difficult to get to the leads when they are in close proximity to other components. The temp control helps because if you go too hot the traces on the board can want to lift. If you wanna practice or see if your up to it find anything with a circuit board that you don't care about and see how it goes.
Looking at the pictures in this thread below there's not that many caps to do and the spacing between the parts is large should be a quick job.
http://www.audioheritage.org/vbullet...234-crossovers
Allen