I can't find the right pump union for my Jacuzzi magnum force outlet piping. I am assuming the inlet size is a standard 1 1/2 " schedule 40 PVC pipe. Are the threads national course threads and is this union a special half union with a rubber seal?

the pump is pumping and circulating hot water into jacuzzi, it will get hot. I think it is ok

Jacuzzi (Carvin) Magnum, Force & Plus pump parts are hard to find.
Here is a link to our site which has a parts explosion/diagram for those pumps.
Jacuzzi Magnum, Magnum Plus, and Magnum Force Pumps

Check your suction plumbing to be sure it is sealed and tight. Then force some water through the pipe to see if anything is blocking it.

You can run 2" all the way if you want. I f you have 1 1/2" coming from the filter you will have to bush it down at some point.
If it comes from the filter in a larger size it will be best to run that size to the heater but 2" probably wont hurt.

Go to your local pool supply get a union to match the sise of your pipe ... or ... just glue it together today and add the uniion next time you have to take that part out.

There two plugs on your pump, one one the side of the pot at the bottom and one dead center of the pump housing on the front. this will only drain your pump if you live in cold country and are winterizing you will need to drain all your equiptment filter, heater and any thing else. then you need to drain your pipes and seal them at poolside to keep the water out.

here's a site where I found tons of jacuzzi parts and accessories.
http://calwesthot1.reachlocal.net/AdvancedSearch.aspx
under select catagory scroll about half way down to jacuzzi pumps and hit search.
If you find what you need can I borrow the jacuzzi .. lol

Good luck...Jacuzzi went out of business. The best source I have had for their parts is CCO:

http://www.jbparts.com/jbc0001.html

The best way is to cut the pipe out and repipe. I'm guessing that the pipe on this is a ridgid schedule 40 PVC. On the new units, they don't use ridged pipe much anymore. If you do decide to cut out the pipe and replace it, it is possible you might have to replace one of the jets depending on how they are mounted to the pipe. Make sure you use primer and a glue that is made to use on wet pipes. You can get it at the hardware store and it's blue. It's the type that you can use on sprinkler systems. You can try the epoxy but you need to make sure that the joint is dry and clean before applying it. Like I said, the best way is to cut out the old and replace with new.