After 2 units failing in the last 12 months and 2 different 'professionals' at over $1000 the problems did not get sorted until I bought one of the vacuflush vacuum gauges from marinediscounters.com and followed the procedure.
Troubleshooting moves instantly from speculation to a process of elimination. Still took a bit of work
, but was all logical with the gauge.
One system had 2 things wrong and the other 3. With that sorted neither of them cycle in 3-4 days (without use) which is - perfect!