Good pics - good idea to ask before doing -
I will advise - DON'T sand the contacts - use a cleaner - this topic is about opinion and everybody has one. Use a fiberglass eraser (sold in art stores and elsewhere). Or use Brasso but be sure to clean the contacts afterwards with alcohol. Then lube the contacts up with PBR-GREASE (sold by Pinball Resource) - or others like to use Teflon lube. Some like to run without lube also.
To meet your goals you will be testing and tearing apart all the score reels to clean out the gunk - sprays and extra lube to free a stuck mech is usually temporary. You will need to understand how to inspect, clean and if necessary adjust a leaf switch. Looks like others have been in there and may have messed things up.
There is a FB group for bowlers and such as well.