Hot tubs pumps have two jobs: circulation (required for heating and filtration) and massage.
Some hot tubs have separate pumps for these two jobs: one pumps for circulation and one or more for massage. Other hot tubs have a two-speed pump to handle both jobs: filtration on low speed and massage on high speed.
Make sure that your pump is non-repairable before replacing it. A pump that does not spin, but buzzes and gets hot may simply need a new capacitor, which is much cheaper to replace than the entire pump. This is almost always the cause when one of the speeds on a two-speed pump fails, for example.
The pumps that we replace instead of repairing usually have one of the following problems:
Worn motor bearings (the pump turns, but not smoothly and with a grinding noise)
Spindle locked up with rust
Water in the motor
Note that two of these three causes of pump death are related to water leaks. If you notice that your pump is leaking, repair it right away to avoid having to replace the entire pump a few months later!