I have a Watkins Classic series model f. 1995? I have power 120 volts to the tub outlet, but the tub will not come on. I've checked the heater and tub reset buttons and both are pushed in. I checked the outlets for the pump...etc. coming out of the tub panel and very low voltage...Any thoughts? Does anyone have a wiring diagram? Thanks for your help!!!!

I don't have a diagram, but I have basically the same tub and it's pretty simple in there. I'd pull the pack and check continuity across the resets to be sure they're actually closed.

Take the two screws out of the back of the GFCI plug, pull off the cover, plug it back in and
check to see if there is output voltage on the GFCI plug.

Alright...I have continuity across the resets and i checked the plug.. I removed the service pack.. I have 120 volts to the service pack... I checked the "switch"??? labeled number 111..If i hold down the switch so connection is made, then i can press the jet switch on the front of the unit they work.. Your thoughts???

Does your pack have an interlock on it? It's a switch that gets pushed in when the service panel is closed, like the light switch in your fridge. It may also be a magnetic version like a door or window alarm. If you have one check continuity across it with the switch manually closed.

OK. Thanks the problem was the interlock. The jets now work, but the tub and heater keep tripping. There are 3 copper "probes", one goes in the heater core, one goes into one of the hoses, do you know where the 3rd one goes? Could this be causing the resets to trip? Thanks again for your help with the interlock.

Glad it was that easy! Those things can be a nuisance.

Two probes go into the plumbing (thermostat and tub reset, thermostat first), and the other smallest one goes into the heater (heater reset). Which button is tripping?

Both are tripping.. I've put the smallest (shortest) probe in the heater core. The longer (thicker) probe and the other probe (thinner) but not the heater probe into the plumbing. Does the thinner or thicker probe go in first? I've never had the resets to trip before. Recently, I ran a new 20 amp individual circuit just for the tub. I'm sure the circuit to the plug is fine. After that, I'm not sure.

The thicker one goes in first.

The heater reset will trip due to bad circulation. Your circ pump may be going out. The tub reset needs the water to overheat which would only be caused by a bad thermostat.