Hi Madams - welcome to the forum!
What you're describing is usually related to an iffy solder joint that has gone bad/non conductive over time. When you mount the pcb into the enclosure, there is typically a little torsional stress when you bolt everything down, and sometimes that can cause a solder joint that was holding okay to fail over time. The best thing to do is to disassemble the pedal and reheat all solder joints (take all the chips out of the sockets before doing this). We have try to narrow the issue down to one area, but hitting everything at once is typically much faster. It's what I would do if it were my build.
Also, make sure and play with the trim pot. Those things can drift over time too. I recently did some mods to a vibrato pedal, let it sit for a while, then started gigging with it. I noticed when I hit it with humbuckers, it would clip really badly. I rearranged my whole pedal board to put that pedal up front so it wouldn't see any boosted signal, but was still getting a lot of clipping. I finally took it off the board to record voltages for a troubleshooting thread; realized I never re-set the trim pot after doing the mods!
Works like a charm now.