I have a jacuzzi z150 with 2 motors. The unit works fine when on low speed. When I switch to High speed the motor kicks on but only a very light stream comes out from the jets.

I switched the motors (the one that was on high to the low speed connection and vice versa). The motor that produced a light stream on the high jets produced the same light when connected to the low speed. The motor that worked fine on the low speed also worked fine when connected to the high speed.

Do I need to replace that one motor or can there potential be a simpler fix?

Please advise. Thank you.

check to see if that motor that barely puts out any water is actually turning, and if so, is it at normal speed? Also, just for kicks, make sure it's turning the right way. If all that is a go, check to see if perhaps the impeller has broken inside the pump housing. If the motor isn't turning, replace it, and if the impeller is broke, you can try to replace that alone. Other than that... ?