Always ask bakery or deli workers about day-old deals around closing time lol.

Honestly, "drifts worse than before" would make me want to throw the controller across the room. That is SO frustrating, especially after you followed a guide step by step. I'd put money on it being cheap junk modules, not your soldering. A lot of those cheap kits online use low quality potentiometers that are already defective or really sensitive to any flux residue. Ngl, I've been down that road and it's almost never worth the hassle unless you get name brand replacements. You probably did a fine solder job, the parts are just garbage.

Oh man, I felt that in my soul... spent a whole evening once hunting down why my dice rolling script kept crashing. Checked every line three times, even rewrote half the thing. Finally realized I wrote "elif" instead of "else if" and python just noped out. Stared at it for maybe 20 seconds feeling like the dumbest person alive before I fixed it. The worst part is you know it's something stupid but your brain just refuses to see it until you've suffered enough.

Nah, the wrap-around method is the ONLY way for tight fits.

Double the force" - that's actually nuts. I mean I knew there was a difference between cheap and decent knives but I didn't think it was that much. Sounds like you've been working way harder than you had to for two years now. That would explain why my arms would feel dead after a big drywall day too. I bet you notice it pretty fast once you get that flex blade in your hand, the mud should lay a lot flatter.