[WFBowen]

Remotely diagnosing electrical issues is usually a crap shoot and can sometimes cause even more problems. My suggestion would be to disconnect the battery, then very carefully mark which wires go to which terminals on the suspect relay. Once you’re absolutely certain of your labeling, carefully remove each wire followed by removing the relay. With any luck, you’ll see a wiring diagram on the relay which shows inputs and switching functions. Now you can try a modern relay with the same number of spades and carefully reconnect your wires. A safer way to proceed is to temporarily splice in some inline fuses then connect one at a time, each time putting the battery cable back on, then trying the various light switch functions. The inline fuses are a good idea not just to protect the new relay (they’re cheap) but to avoid damaging your existing wiring. Used oem relays IIRC are nla and buying a used one is a crap shoot and, because you’re not certain if actually functions as new, will just complicate the situation.
Hope this helps - it’s really just a starting point.
Bill