[Jim c]

The 3 term switch should have power to the centre term.
Power will go to other term when you move the switch to L or R/H pump.

Use a test lamp at the switch first and see if it is doing that.
If it is go to each pump with the test lamp , it will light if switched to that side.
If it lights check the earth by putting the test lamp earth clip to the pump earth it should light when you probe its power again.
If it doesnt it is the earth.

If you have power and earth its the pump.
If you dont have power start looking.

jim