Hi Rob, sorry to hear you are having problems, it was a great machine.
Maybe it needs wiring checked for loose wire or something regarding the vac.
As for the pump, now and again i woud put an open ended hose onto connection
and run it for a minute or two, ensuring machine dosnt empty, sounds like it is purging,
this worked for me, when it happened occasionally.
Just to add i only sold it as i picked up a Scorpion secondhand, which at the
time where as rare as hens back teeth

Could the machine have been damaged by frost.
Amtech are the main dealers you could ring them.
Andrew