I have an old Cal Spa PS2 and I just replaced the element. After getting the circulation going, (bleeding air), I now have a problem with the jets. When I turn the jet pump switch on, the pump sounds quite loud and strained, like it can't pump or something. If I leave it on, it cuts out (I think it overheats?). I let it cool down and then the circulating pump works okay again, but the jet pump is the same, just a very loud hum and no pumping. When I changed the elements, the water drained out of the pump, so I am thinking maybe the jet pump needs to be bled of air?
Any help please? Weather is cold and I want to soak.

Have you had this spa running prior to replacing the element? It almost sounds to me like the motor is either locked up or not getting proper voltage (for instance if it's a 240V pump and only getting 120V). If you can, try to turn the impeller or shaft of the motor (with power disconnected of course) and if it spins, see if you can notice the shaft turning when you do have power applied. Check voltage on the pump as well, to be sure you have full power. Could also be bad bearings, physical obstruction, bad capacitor, etc. Running a motor dry (no water) will only destroy your shaft seal on the pump, not the motor itself.

Thanks for the input.
The spa was running fine before the element went, water level okay etc. and the jets worked great. I replaced the element, opened the knife gates to let water back in, fired the power on and bled the system. The heater works fine as does the general circulation pump, but when I push the jst button, it only moans loud and then if I don't swicth it off, it cuts out, not flipping the breaker, bhut apparently just overheating? Then neither pump works.
After awhile the circulating pump will come back on when I turn the power off and back on. Then the same thing if I hit the jet button. I should mention that the jet pump appears to be attached to the circulating pump, as if they are one unit. I don't see where I could spin the shaft? Maybe I'll have to take it our to do this and check it out? As it is, I can use the tub fine the way it is, but it would be nice to have the jets working.
Anything more you can suggest based on this extra info?

just out of curiousity, what part of the country are you located in? Have you had freezing temperatures during the time the tub was drained? The reason I ask is that I had a spa that had something similar happen (last year) and the water that didn't get drained from the main motor had frozen and siezed the impeller. It wasn't until about 2 hours with the knipco heater directed at it did it finally thaw COMPLETELY to operate again. You definentally don't want to start it with a little ice left inside. Could this be resembling your situation?

I did keep the circulation pump on when the element went until I got a new one to change out, but the temp. was below freezing outside, so maybe the jet pump water froze even though the circulation pump was working? I can put heat on it for half a day and see what happens. This would certainly be the easiest fix, and I can see how if it did freeze up, it might have locked the impellor up and with no water flowing through it might have ice still in. I'll give it a try anyway and see. I am away with work until Thursday but will try then.
Thanks.

The circulation pump bypasses the main pump, so the water in the main pump was not being exchanged with water.

Hopfully you don't have broken plumbing components also, since the circulation plumbing is not part of the main plumbing. It uses separate lines so all your main jet lines didn't have water circulating either, they may be froze as well.

Sadly enough, when a person looses a heater element in the winter and they can't replace it IMMEDIATELY the best thing a person can do is go to the local farm supply store and get an immersion heater for a stock tank and suspend it in the middle and keep the circulation going. Even just draining a tub isn't enough since water is always trapped in the system.

This doesn't seem to match what I see in my system. The pump which circulates and the jet pump are contained in one unit, with the circulation pump on one end and the other motor on the other. Both of these have only one outlet. The pipe which comes from the tub, (return pipe?), goes through the magnetic swicth, then through the pipe with the element, makes a 90 degree turn to connect to the circulation pump and then on to the tub pipes, which send the water to the tub. There is no line whatsoever going to the jet pump. The jet pump, (or motor), sits behind the circulation pump and from what I can tell it just drived stronger pressure through the circulation pump and out into the main piping. No separate lines at all. Is this making sense? I'll still try to put some heat on the jet motor to see if this works, but I wanted to make this point clear.
I've included a rough sketch of the pump and control box area.

Ok, that pic clears up a lot. You don't have a circulating pump. You just have a 2 speed jet pump with a flow through heater. The part that you have labeled as a main pump is actually the motor. The part that looks like a solenoid is actually a capacitor. The part you have labeled as the circulation pump is actually the wet end, or main pump. The flow is actually flowing opposite the direction you indicated. Since your low speed is working, I would suspect either the high speed windings in the motor went bad or the capacitor. Although it is very unlikely, a 2 speed motor will act like that if both low and high were engaged at the same time. Normally when you switch to high speed, the low will disengage.