I have a Vita Spa, it is probably 25 years old. It has worked fine over the last several years, until lately. It had a small leak without my knowledge and the water level went low. Now the unit will not heat unless the jets are turned on. Does this sound like an issue anyone knows about? Please let me know anything I need to check to figure this issue out. I am new to working hot tubs, so any help is much appreciated. Thank you!!