i'll note i replaced my circuit board 2 times.
the original circuit board : you can clean the copper i used kaboom and it shined the copper up like new, Problem the 40 year old mylar was brittle and the contact areas where the bulb sockets touched were worn out.
when i changed out the old voltage regulator on the board i broke the mylar and snapped off one of the regulator connectors, also the copper around the main connector started to de-laminate from moving it around.
enter repro board #1
I swapped the board and i had it in the car about 3 years. I was using the normal 194 bulbs and i decided to go with the HIPO kit.
when i pulled it i found the copper was again de-laminating. i was having problems with one bulb and i kept pulling the cluster and eventually one of the copper contacts actaully broke off.
enter repro board #2
i kind of learned my lesson and i took clear tape and carefully around the edges of the copper where the connector goes i wrapped the tape around the ends to keep the copper from popping off the mylar.
i also put a couple of pieces around 2 bulb sockets that i had an issue with in the past on my car, this board has been in the car for over 5 years and i just did the swap to the next gen LEDS on it.
the black bulb sockets themselves are the cause of problems. the Plastic itself suffers from 40 years of degrading from the heat of the 194 bulbs, many times the sockets will break apart in your hand from just touching them. 10 years ago i had to find replacement sockets from a junk car to replace many of mine that had fallen apart.
the metal contacts are 2 piece and they slip into the plastic, these get corroded. i soaked mine in rust / oxidation remover a couple of years ago and i also coated everything with dielectric grease to try and protect the metal from corroding again.
this worked pretty well i had 2 sockets that required me to bend the outer arms a little to get the bulb working.
sometimes somebody bent the socket arms too far because they got angry with a light not working when you do that you can tear the copper pcb wires on the mylar then you get to replace the circuit board again.
i know one friend that soldered jumper wires from the sockets to the circuit board. its possible with a low heat iron and thin solder.
corrosion on the circuit board just causes bad contact so you hit a bump and a light turns on and off, the copper is wide on the mylar so that is not the issue. the only time i would replace a board is when the mylar cracks, the copper peels off the mylar, or the copper is torn, everything else is the tension you set with the bulb sockets.
a word of caution on the next gen LED bulbs. there are many manufacturers. i ordered a specific bulb that has a filament of wire for the bulb contact on both sides, many just put the filament on one side of the bulb i figured 4 connections is better then 2
example.
the filament is bent around the base of the green plastic giving you contact for both wires on both sides of the case.
this version only has the filiment on one side and is cut shorter so you only get contact on one side.
the double filament makes the bulb base thicker and it holds in the sockets with more tension.
its a small difference but it can make or break you.
i can give the ebay link to the bulbs i bought but the seller is pretty terrible,,, example i bought 20 led bulbs, 18 came and he sent me some kind of adjustable IR circuit for a remote and a made in china Iphone charger that will most likely burst into flames if used. the seller grabbed a bunch of boxes off the shelf and shipped me the stuff so i know it was a mistake but his rating isn't very high... i figured for less then 10$ with free shipping it was worth the risk,,, the bulbs cost me about 7$,,,, verse 75$ dollars if you buy from a more reputable vendor.