I just refilled my Hot Springs 1997 classic and tuned it on it worked for about 10 seconds then the gray box on the end of the heater made a clunking noise, it says watkins no fault on heater and has two silver tubes and a grey box on the end that made the clunk noise then it shuts off and the lights blinks. so i drained some water out and put the garden hose down inside the middle filter tube the grey one and then turned the tub back on everything worked with the hose in, the jets and i can see heat coming out the grate in the bottom but when i pull the hose out it just shuts off and blinks so i am thinking its the circulation pump? just a guess i have never worked on a hot tub before and help or advice would help thanks

Circ pump sounds like the culprit. Test for voltage to be sure, though. If it's getting voltage, it's bad.

thats what i think it is to i pulled the pump off tonight and took the the imprrler housing off and pluged it back in and turned it on and it just hummed and kinda turned thanks for the reply