Phil. To take your second point first. Don't know what the resistance is though I could measure it if you really need to know. What I can say is that my experience of a dozen or so pumps that I have rebuilt none have had a failed body.
As to your first point. Yes the diagram should be tensioned when tightening up the 2 back screws which hold the two, or three, parts of the body together. This gives the diaghram more freedom to do its job. It is difficult to do with the points throw over mechanism, which you have just adjusted, in place. The only real way to do it is by shorting the points and putting power on it so that the coil pulls the armature up while you tighten the screws.
Ian
Notts. UK
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1. The SU book says nothing about tensioning the diaphragm when tightening down the perimeter screws. Yet I know I've read somewhere that the center piece of the points should be wedged up to pre-tension the diaphragm when assembling the base to the body/new diaphragm.
what's the right answer on that?
2. does the electromagnet in the body ever go bad? Does anybody measure the resistance hot/cold?
thanks.
phil