My friend has a Cap Spa that was made in 1987 is still in good shape. One day it stopped heating the spa. So they replaced the heating element. I went over there this weekend because they were having pump problems I got the pump fixed. When we turned it on is starts up great and the heater on light comes on and the pump runs on low speed to heat up but never does. Didnt bring meter to check power to element. Also with pump running sounds like element is rattling in heater tube. Any help would be great.

Heater rattle is normal. Try rotating the element a little to see if it'll stop. It's just turbulence in the heater element cavity.

You've got a light to the heater, just remember it takes a bit of time for it to actually heat up the water. ie, your heater will not be warm.