I have a MIT GE-7 and the thing is really starting to crap out on me. Periodically the volume would cut out and often the thing cuts out all together....I don't want to give up on this one...
Some of the Boss pedals that have been arriving here lately have behaved this way during the first moments of usage also. The contacts on the 1/4" jacks seem to be prone to oxidation build-up.
One cleaner that's good for this sort of thing is Caig's DeoxIt... I think that at some point in the near future I'm going to make a maintenance project out of this, giving all of the amplifier and pedal jack contacts a burnishing. Way back when (I have a hobby of restoring old shortwave communications receivers), I was only able to find this stuff in small spray cans with a needle nozzle, but now it looks like there are a lot more choices (the pen, squeeze tube and brush applicator look like they'd do the neatest job of getting inside enclosed 1/4" jacks without making a mess).