I have a behringer uv300 vibrato that sounds Great. I sold my 1982 VB2 and use the behringer instead. They both add some noise when effect is off. I dont have much knowledge reading schematics etc, but i have built a couple of pedals, and i have seen People rehousing and modding these eith TB. I have no problem with the plastic case. I figure that I can fit a 3dpt switch if not running a battery.
So, is it at all possible to in someway add a footswitch that bypasses the signal when off, without desoldering a lot of components?
It's probably possible. However, I would recommend building a looper instead and putting the vibrato in the loop. You can make it true or buffered bypass, serial or parallel. I like to use vibrato before or after a short delay, which is set to 100% wet (no undelayed sound) and then mix that whole thing with the dry sound in parallel. Goes from subtle to very trippy. Point being: custom loopers give you a lot of freedom.
Hop that helps,
Andy