Are you sure it is a defective relay? Usually the solder cracks around the 5 terminals on them. Resolder all relays as well as the joints between the main board and the two boards that are mounted at right angles to it. Add a bit of fresh solder but take care not to bridge between traces.
Also a must for these cars is to add a series fuse in the auxiliary water pump circuit as it can badly burn the pushbutton assembly if (when) it seizes. I think I added a 1 or 2 amp fuse.
If you indeed have a defective relay, probably someone has a used one that they can send you. If you can't find one I can give you one for the price of shipping but it would be coming from Canada so hopefully you can find one closer.