we finally got all of the leaks fixed and got the filters cleaned, but still no heat. the red indicator light for heat isn't even on. both pumps run, the jets work fine. what all do i need to test to see why we don't have heat. it is a 1992 Dimension One Spa, the heater was replaced in 2001. Please help

Locate your pressure switch. It should be located in the heater housing. What you can try, as a test, is to remove the two wires that go to it, and short them together. If your heat turns on, then try to adjust your pressure switch with your pump on low, by turning the knurled knob counter clockwise until it clicks on the heater, and then one half turn more. If shorting the wires doesn't turn on the heater, your thermostat may be bad. You should hear a click when turning from minimum temp to maximum temp, with everything off. This click will be very subtle. If you don't hear the click, suspect the thermostat. If that seems to be ok, and the pressure switch is ok, then suspect the heater contactor (relay).