A/C Issue

I've never seen or even heard of "shared" start capacitors. You must be referring to run capacitors where are often shared. It that is all there is there must not be any start capacitor for the compressor. Start capacitors are never used for the fan motor because the sudden start would damage the fan blades which should come up to speed slowly compared to the compressor. If it were me, I'd leave the "softstart kit" on the system. All RV air conditioners used to come standard with start kits (a start capacitor and relay) but from what I'm hearing, mfgs have stopped doing that - bad idea in my book.

The only way to know if a capacitor is "weak" is to have it tested with a meter - about $15 and up on Amazon: https://www.amazon.com/s?k=capacitor+tester+meter&crid=X01HAKMEMSRY&sprefix=capacitor+test%2Caps%2C237