Wow, I read that a vinegar soak can break down old plastisol too.

You mentioned your line work is still messy and you wonder if a screen tablet would fix that, but can I ask what specifically feels messy about it? Like is it the shaky lines, or that you can't get the curve to go where you want, or something about the pressure? I only ask because those three things have pretty different fixes and only one of them is really about the tablet. A screen might help with hand eye stuff since you're drawing right where you look, but if the issue is control or pressure settings, a Cintiq won't magically fix that either. Have you tried messing with the smoothing or stabilizer settings wherever you draw?

I used to figure shims and clamps were hack work that would come back to bite you. Then a guy showed me how he fixed a drum glide on an old Kenmore with a piece of nylon cutting board and it ran quiet for three years. That taught me the real question is whether the repair holds up, not whether it came out of a kit. A paint stirrer is soft wood though, so I would keep an eye on it for wear and make sure the clamp is not rubbing the drum.