The best fix I have found for the GPR is the one made by KEM. The biggest issue with the Fors relays, and others built to that exact design, is they have a "limiting" pin inside that limits full engagement of the relay contacts. This causes arcing, and burns out the contact areas; thus a clicking relay, that doesn't work. The KEM part eliminated that pin, allowing full contact, and longer relay life.
Normally, I am not a KEM fan, as they are one of the lower end parts brands. But, in this case, they have come up with a superior product. Maybe not by design, but that how it worked out.