How do you know when it's time to replace your sump pump? Some signs that your sump pump can't be repaired include: noisy units, it stops working completely and electrical problems.
Noisy Units - If your sump pump is making a load noise the entire time it's running, either the impeller is bent or the motor is going out. Turn your unit over and remove the screen, using your screwdriver. Inspect the impeller. If it is bent, you have no choice but to replace the unit.
Stops working Completely - If your sump pump doesn't turn on, first check to make sure the unit is plugged in and getting power. Make sure the breaker hasn't tripped in the main panel box. Use the electrical tester.
Manually operate the float to see if you can get the sump pump to work. Check the float switch with your electrical tester to make sure it's showing current. If the float check out OK, your motor is probably burned out. Replace the unit.