Hello,

The RSR is also used in 940 model. I've opened this relay and tried to solder the connections inside. Well to my surprise there is no circuit board. The components are quite basic - there's no protection diode either. The components are all connected by welding. So there's nothing to solder (not like fuel injection relay).

What could actually fail are the relay contacts (referring to inside the relay box). I've tried sanding its surfaces with a very fine sandpaper (grit number 600 and above). This worked in my case. But if the contacts are badly pitted you better get a replacement. Pitting refers to holes on the contact surfaces. These reduce the current flow area hence the need to replace.

Another thing that could fail are the contacts inside the relay connector and the relay's external contacts - due to corrosion. These corrode when the silicone/rubber insulator break down due to age. You could clean the contacts using a very fine sandpaper rolled into a small size that could fit inside the contacts. A simpler way is to spray some penetrant (like WD40) on the contacts and repeatedly connect/disconnect the relay. But nothing beats a proper cleaning.

For a properly designed tool to clean these external contacts see:
http://www.ipatools.com/products/index.php/ipa-8048.html

Regards,
Amarin.