http://www.bmwe34.net/e34main/mainte...capacitors.htm

I'm about to do this myself to see if it helps the fuel guage issue I have now, and a flickering odometer.

When I say resolder the board, it's just my habit that when I've got an old dashboard torn down to replace components, I examine all of the soldered components and wires carefully to see if any of the solder joints look "Cold" (dull) or cracked, or even burned. If I see any problems, I'll remove the old solder and re-do it with new flux and good quality solder. I'm degreed in EE, so I'm fairly handy with a soldering iron and can usually spot the problem areas, but any careful examination with good lighting will be worth your time while you have it apart.