Your motor unit makes unusual noise.
Poor water circulation in the filtration pump.
Check that the water line in the pool is between the min and max limits. If this is not the case, fill or empty your spa so that the water line is between its two limits.
Clean the 2 nozzles (suction and discharge) inside the basin. To do this, just unscrew these nozzles and remove any filth (hair, fur, dead skin...).
The problem may be with the filter cartridge. Dissolve the filter cartridge and clean it with a jet of water (do not use a high pressure cleaner).
If the problem is not solved, run the spa by removing this filter for 24 hours.
If after all the required tests and replacement of the filter cartridge, the problem persists, you have to replace the motor unit.