I had run out of propane so I hadn't used my tub for awhile. Tub worked great before that. Went to fire up and there was no power at all to heater. Had a tech come out and tell me it was the transformer. Ordered one and put it in. Got power and now the hi limit light comes on without even firing up at all. The water is cold. It was working fine before and now this. I read up about some new parts to consider. What's happening? All of a sudden everything is needing replacing? I'm just asking what to check next. The hi limit is on and the water is cold. Cleaned out filter and can feel and hear water running through heater and also have good flow at hot tub. Any thoughts would help greatly. Thanks.