Stuart turner help

I have a Stuart turner monsoon pump. A few months back it would stop working. I found that resetting the trip switch would get it back working until a few weeks ago it stopped. I changed the start capacitor and it worked for an hour. Any advice on what else to try. Could the pcb short out the capacitor. Also I have night saver electricity and that element trips a bit, however it only comes on at night and I have not used it in nearly a year. Could this be the cause?In fairness it has helped my electric bill. Anyway any ideas on what to try next, it must be electrical as with a new capacitor it worked for a while. I intend on getting a multi meter to see if the capacitor is actually dead. Would appreciate any help