In the above image you can see how evident the fracturing is at the points circled in red. The blue ones are getting bad, and the green ones will follow. The red points have an air gap that allows for oxidation, and even though they are physically still in contact, they cause an intermittent problem.
The ABS plastic housing that contains the board is guaranteed to have degraded and become brittle. Once you start to remove it you will see this. It will crumble easily, but will also have to be tore off due to the insulating compound sticking to it.
You can easily just strip it off, solder all the joints, wrap it in electrical tape and just let it hang inplace once you've reinstalled it.
Over time, as I have observed that in every case I have dealt with, the pins on the relays were the problem, I have developed my own procedure that allows me to save the housing, for the most part, and retain the mounting tabs. It is illustrated in the following.
First, using a utility knife, I score a rectangle that will be the area I wish to remove. Scoring it this way will help keep a decent edge to the opening I will create. I score it as deep as I can without breaking through the housing. I don't wish to go through and take the chance of cutting through one of the traces on the PCB. I then scrore it diagonally. This allows me to push down in the middle of the scores and crack the section inside the rectangle.
Once I have an opening I use needle nose pliers to remove the rest of the plastic.
You will have to remove the insulating compound. Get this area as clean as you can, and wash your hands after handling this stuff.
Once you've got it as clean as you can get it, reflow the solder joints with rosin core solder. Don't use acid core because it will only cause corrosion. A fan lightly blowing across your work is advised, because you don't want to breath any fumes from the insulating compound that may be left.
Now some at this point may say that they aren't any good at electronics, and don't think they can do this. With a $5 soldering iron, a $1 roll of solder, and twenty minutes of research on the web about how to properly solder, any of you could do it. If not, then these old cars are going to be way too much for you.
After I'm done, I tape over the opening (here I've done it with black duct tape), and it is ready to install like it originally was.
You could also remove all the plastic and compound from this side. Since all the components are soldered from this one side, you could reflow every point on the board. I would leave a border of 1/4" - 3/8" remaining to keep some structure around the mounting tabs as insurance from them breaking off though.
I don't know what you have to spend for these modules at your local yards, but the ones here let me snag them for $5. I keep a repaired one with me most of the time. I have sold a bunch of them. On more than a few occasions I have spotted someone with their lights up, and sold them a module on the spot for $40. One lady I even installed it for her in the grocery store parking lot, and she forced an extra $10 on me. With the 87 - 88 units it is so easy to pop the dash cover and show them where it goes. So you can see where it can earn you some extra cash. Module for $5, and the repair takes less than 20 minutes. You might be able to get more than $40 for it, but I feel pretty comfortable with that price. I'm profiting, but I'm not gouging them either. Another plus... "Hey, you're into these cars and I was thinking about selling this one, so I figured I'd give you a call..."
Later I'll try to get a picture of the module mounted in its location to add to the beginning of this.
Also, maybe I'll go find the other style modules and add their repairs. Maybe someone else with them can provide that info. I don't particularly care for the 90+ interiors, so it's unlikely that I'll have one in my posession anytime soon.
If the mods believe that this was explained in a clear manner they could possibly sticky it. Might save some trouble when the inevitable question arises again and someone doesn't understand the search function.
If anyone feels I should add something I missed, or would like to merge their info into it, just let me know. Someone please clarify the years that Le Barons used this module, If you will.