buzztec

I have a Four Winds Titanium Spa with a Balboa GS501SZ system and a Balboa VL600 control panel. It is about 5 years old. Jet one is 2 speed and jet 2 is single speed. Recently jet one has been switching itself off and then on again after a few minutes only to go off again a few minutes later and continuous this cycling on and off. I have no error messages and I took out the filter just in case there were flow restrictions, but it did not solve the problem. Can anyone please shed any light on this behaviour – thanks.