MM 212 sixty five gain/clean switch

Hello Folks,
I am a happy owner of a 212 sixty five in mint condition. I absolutly love the sound of this amp.
Heres my question:
Is it possible to add a footswitch to activate the output tube gain to the circuit?
I like the sound when I have the master on 4 and the volume at around 7-8. It starts to crunch a little bluesy/ stones like. Is this setting driving the output tube section?
I would like to have an option to go back to clean from there without touching the master and volume contol, for using it live in my songs.
Are MM amps simply not made for this?
I also noticed some kind of twang or tremolo when I use the second channal. This also appears when I havent activated the tremolo on the footswitch. I find that the first channal has a more defined clean sound. Is that normal?
Thanks in advance. I hope you can give me some info on that in order to keep my mm last long.

You can use a A/B/Y switch to switch and bridge the channels,Just a thought..........