I use my bike chain lube.

Just a thought...

Have you measured red to black? If the answer is 240, the situation may be a bit different than you think.

Black is usually hot. Whether it's line or load I can't tell from a picture after things have been removed. Red would typically be going from a switch to an outlet or light. Or whoever did the original wiring ran out of black and used red. It happens.

White is neutral. Black and red are hot. Red, usually is switched hot.

If the pipes look good, don't fix what ain't broke.

PVC is a cheaper alternative to metal for new construction or repairs, it's not necessarily better.

If it hasn't been submerged or run much, the pump itself probably has life left in it. Still, pumps are cheap and a critical item so it makes sense to replace.

Absolutely replace the check valve. Rubber seals deteriorate over time whether they're used or not.

In my Chicago area suburb, the code guys are generally pretty helpful.

Furnace is only used 6 months out of the year. I replace batteries in mine (and check expiry date...) at the same time I turn the furnace back on.

If there are any pigtails in the junction box (wirenuts) undo them and re-do them to make sure there is a good connection. Could be getting some minor arcing or a high resistance contact if they're not solid.

I had treated timber as perimeter for my brick patio. After 25 years, most of them disintegrated. I replaced them a couple years ago with recycled plastic timber. I should have used plastic the first time. Not sure how prices are these days....