5k tqcs after run relay problem (repost)

[Kevin Boothroyd <kjb@blackmarket.mv.com>]

This is a repost of a question from last week

I own an 87 5000cs Turbo Quattro.
My after run relay does not switch the radiator cooling fan on.
It does switch the turbo coolant pump on. Temp sender good.
The fan will switch on when I bypass the relay by removing it and jumping
the necessary leads.
The relay is probably bad but I would like to bench test it before
spending the $100 for a new one. I also want to be sure that if I do
replace it I wont damage the new one. I have already tried a used one and
possibly damaged that one.

Any help on bench testing the relay and wiring is appreciated.

Reliable sources for used relays?

                thank you
                         Kevin Boothroyd