My comments on the Pistonola were a reaction to the feeling I was
getting from earlier notes that when something is not easily understood
then it must be wrong!  We should also separate the advertising man's
puffery from the inventor's work.

If the original concept and machine were correct, then when we can't
see how they could work it's up to us to find out.  With different
skills and the benefit of hindsight we may well identify flaws and
corrections that the original inventor never did.  We certainly have
good knowledge about how machines fail, and how design changes could
have prevented problems!

I suppose a Pistonola problem could be leakage at the relatively high
tensions used.  Another could be mechanical effect of the higher forces
acting on components.  From what I recall reading, the problem with
Pistonolas was that the pistons tended to stick.  Perhaps the high
tensions didn't help, because when they jammed they really jammed?

Paddy Handscombe's view is that the rubber cylinder head gaskets crept
slightly and blocked the pistons.  The matter has never been resolved,
as far as I know, because rebuilders just concentrate on other things.

Julian Dyer