DD writes "A good pump should last 10 years minium if fitted
properly. Cheap pumps
dop't last."

Well I've been lucky then, or by good fortune fitted the pumps
properly, as I've just been back to my old notebooks and the pumps
have been in now since late 1988, and I wouldn't have had the cash
then to go for gold plated ones.

It could of course well be that operating to and from the neutral
point of the Dunsley reduces stress on the pumps .... possibly!!

Tomorrow of course now they will both fail!

Rob