What a mechanical nightmare! Those shiny copper-colored components are called "relays". "Ree" "Laaaaazzzze" You won't see them anywhere else in a control unit except if you visit space station MIR as a tourist!
So far, I've found one cracked solder joint on the smaller sub-board and one cold solder joint on the larger board. I can see where someone reworked a few of the joints previously - either a rework facility or a previous owner. I'm taking no chances - all solder joints are going to be reheated and touched up.
Now - what to do with those REE-LAAAAZZZZEE ? I'm kinda shakey on burnishing them with anything other than a business card or matchbook cover. I don't think you want to touch them with any kind of metal file (if you should have one that thin). Better to be gentle on their contact surfaces.