Mine was cured by re-soldering the joints on the relay. I also found http://www.newcougar.org/forums/how-tos/122039-power-window-relay-fixable.html very helpful.
One extra bit of info is that there is a concertina rubber seal between the relay and its socket. The seal on mine had somehow become compressed at the bottom of the socket so the cantacts could not be pushed fully home, giving the impression the repair had failed. I found this out when I tried the 'bare' relay (i.e.removed from its case) (to confirm it was definitely the relay failing and not the motor or switch) and the relay worked, but failed when cased. Thats when I found the compressed seal and eased it back into place with a very small screwdiver.
Cost of the repair was zero.
Mark
July 2011