I was gonna say I would ground it to the output jack, that's always been my standard practice building 5e3s. Incredibly easy amp to build if you don't mind cutting your hands to pieces on the chassis
I could have explained that better. Your shielded cable isn't inherently grounded coming from the switch. You're using it as a ground so you need to provide a ground for it. Wiring it to the ground on your power jack will do that.
You could try doing reverse weeding, which is stick the transfer tape to the whole sticker and peel it that way. Makes it a little less tedious. Still sucks, but the white girl CNC is great for pedal labeling