Here is a step by step guide to replacing your spa pump.  Going into this, we are assuming that you have basic handyman skills and know what you are doing in regards to working with electricity and basic mechanics.  If you feel uncomfortable with doing a project like this, we cannot emphasize enough that you should hire a pool and spa professional to do it for you.  The cost is usually too much, and you will come out of it without additional costs or worse, damages and injury.