You don't touch the contact points. To re-solder a relay, carefully pry the cap off and inspect the soldered connections on the printed circuit boards. If you have a hand lens, use that. Usually you can see bad solder joints on the Bosch relays. There will probably be cracks in the solder around the metal tabs protruding through the printed circuit board. Get a 25 to 35 watt soldering iron and some electronic solder. Tin the tip of the hot iron and then touch the tip of the hot iron to the joint to be re-soldered. When the solder melts, add just enough solder to provide a good joint. The local Volvo Master Tech has brough me a few relays to re-solder. I could find no visible defects with the overdrive relay from his own car, but it did not work. After re-soldering it worked fine.

The Radio Suppression Relay (which actually provides power to the fuel injectors) should also be done. I have not had trouble with one of those yet, but several brickboarders including Don Foster have reported trouble with these.