At minimum, you should be reflowing solder on all the header pins on all the boards. Do that first. Next if you are still having issues with some insert lamps out, you have to do some troubleshooting. Is the bulb bad, is the socket bad, is the connection to the board bad, is the SCR bad, is the socket getting voltage etc etc.

Tbh, it is easier to replace the contacts and install new header pins than to clean them with sandpaper. It all takes time, but at least you'll know it was done right. I've worked on a few games now where I would have smashed the PO on the head with my ratchet if I saw them doing the halfassed things I've had to rework. Take your time and do it right.

Definitely don't rush anything. For the short term, it might work, but you'll just be reworking it again in the future. Might as well do it right and have it last for 30 more years. If anything, for the next guy. For me, doing board work has been therapeutic, if anything. There's something satisfying about desoldering the old stuff, and soldering in the new stuff. It's very enjoyable for me. Plus you get the satisfaction of knowing that your work was done well and not slopped together only to be undone by the next guy who would have preferred that you didn't touch it in the first place. Trust me on this

I may have linked to this thread in another one of yours, but if I didn't I would start a list of lamps that are out and start troubleshooting each one. You may find that there is a combination of bad lamps (especially if they're incandescent), bad sockets, poor connections to sockets, and bad SCRs. Make a list and start knocking them out one by one.

https://pinside.com/pinball/forum/topic/paragon-controlled-lamps-only-some-dont-work