[Merv and Sharon]

Yes, I am not going to butcher the spare pump I have to find out. There also seems to be some kind of sealant between the nipple and the body of the pump. So I suspect the realistic options would be to bore the existing nipple out and thread the hole and fit an appropriate plug (I think that the nipple itself is too thin to thread properly) or, stick with the rubber part and the clamp. If that is of decent quality and shape it should work. I had two of the flat topped ones I was given, split (wrong application) but since changing to the domed ones, no problems for the last 2 years.