Thank you Jules ... made my day ... it's rare that any baited line I throw into the water ever hooks a fish! He, he!
PLA seems, from tests to date, to be reasonably bio and methanol proof. I'll fish the samples out of the jars (see what I did there?) later and make a physical check, but visually they've survived several months submerged with no obvious ill effect. Caustic is a different kettle of fish though (see what I did there?). PLA is sometimes used as support in an ABS print which is later dissolved away with an NaOH solution, so don't go dropping any methoxide on it.
Before you rush out and plaice an order (see what I did there?) for a new one, let's see if anyone can magic up an unused or broken item which they can lend us. A whole pump would be even better, because I can check the cover fits the pump. With the TAM 120 cover I printed a thin section (like a gasket) first to check the fit, so the whole pump would be a great help.