I took the valve out and inspected the rubber washers (a.o.k.) and the coil. The coil had a fault where the thin copper wire burnt or coroded. I soldered the wire back and it seems to work fine for now. If a new coil isn't rediculously price I'll replace the old. Thanks so much for the info.

TCCBass...let me know how your venture turns out. Thanks.
Alec.