I have a Crate g120 cxl guitar amp. it is switching between channels on it's own. (no footswitch)

The easiest way would be to contact Crate customer service, or Guitar Center, or Musician's Friend, or Ebay.Here are the links-
http://www.crateamps.com/support/index.php

Guitar Center Music Instruments Accessories and Equipment


Musician Friend Musical Instruments Store

eBayeBay

The Fender Hot Rod Deluxe shows a 2-button footswitch as standard but I'm confused. This link shows it as connected to the amp via a mono cable ... FENDER Hot Rod Deluxe DeVille Footswitch which is impossible using two switches. Normally it's a stereo (tip, ring, sleeve) with tip to sleeve being one connection, and ring to sleeve the other. Good luck with this one.

On some amps there needs to be a footswitch inserted in the control jack to activate the effects circuit. Contact Crate to see if that's the case with your amp.
http://www.crateamps.com/support/index.php

sure, why not, the footswitch connects between the guitar and the amp, with your guitar into the footswitch, go rock that thing!

That is probably a momentary switch that is dirty and sticking. These onboard effects on guitar amps are usually nothing more than a computer sound card and I've found bad connections going to and from them as well. I do think that switch is dirty and sticking, though.

Is this happening only with the foot switch plugged in? A bad cable on the footswitch is the most likely cause but there could also be a problem within the footswitch jack on the amp.

sounds to me like your din plug on your controller is messed up ? hope this helps !

have you tried the footswitch to change channels. also. my amp has to be in channel 2 position (with the button on the head) before i can use the footswitch. sometimes the input/footswitch jack wears out and you need to bend the internal tip/ring tabs of the jack to make better contact. also like on my fender amp, i had just a standard mono instrument cable going to my footswitch and it was acting wierd cause it needed a stereo instrument cable. one last thing on the grounding resistors on the pcb, they get hot and break the solder welds which messes with all sorts of stuff in amps. usually look like sugar cubes , cement resistor. 5watt usually under 1k ohm. check for bad solder welds on the pcb where the big resistors are and the switches/buttons and at the footswitch. there may be a bad ic or transistor for the channel swithing

If the footswitch is not switching correctly, open it up and check for any shorts or a defective switch. Sounds like it's a problem with the switch.