Flo Jet Macerator Pump Stops - Includes disassembly and reassembly instructions

It worked for me - I’m not responsible for any damages caused by applying this fix to your pump
You need to be semi mechanical to accomplish this procedure!

  1. Disassemble the pump using the following steps (mark the motor and pump joints alignment for easy assembly)
  2. Remove the 4 acorn nuts at the top of the pump assembly
  3. Pull the top sewer adapter away from the pump (be careful with the the gasket)

At this point remove anything wrapped up around the chopper blade. This may be all you need to do.

  1. Remove the chopper blade assembly by gripping the motor shaft under the blade with a small pointed vice grips and remove the nut holding the chopper blade.
  2. Now remove the pump assembly, being careful with the next gasket. Examine the rubber pump impeller. Replace if it has damaged vanes.

OK, now you are going to pay attention to the motor assembly. My pump would stop after just a couple minutes of use no matter what the load and the motor was never more than just warm. I expected an over sensitive thermal cut off switch.

  1. You should now have just the motor assembly in your hand. Move to bottom of the motor. (opposite end of the expose motor shaft)
  2. Remove the 2 hex head screws.

Be careful with the next steps!

  1. Slowly remove the bottom assembly. Be careful as the motor brushes and springs will move to the center as you pull the bottom plate from the motor.
  2. Now look at the bottom plate. What you are looking for is a small silver electronic component in a clear plastic sleeve that is held down by a zip tie.
  3. Clip off the zip tie.

The following steps was my fix for the overly sensitive thermal switch. (adding a bit of insulation to reduce the sensitivity)

  1. Use a piece of electrical shrink tubing that snugly fits over the thermal switch and plastic sleeve.
  2. Using heat, shrink the tubing over the thermal switch assembly.
  3. Zip tie the thermal switch back to it’s previous position using a small zip tie.


  1. This is the hardest part of the process - getting the brushes in place!
  2. Using your fingers, hold the brushes and springs back in to their holders. (Take your time not to damage the brushes!)
  3. Now start to place the bottom plate on to the motor assembly (using the marks you made at the start of this process)
  4. Once you get the brushes over the lower motor bearing, they will slide up onto the motor armature. Take your time!
  5. Now turn the motor shaft to make sure everything is moving free. (You will feel some “notchy” movements and the armature moves through the magnetic fields.
  6. Now install the hex motor screws. It helps to hold the motor in the vertical position as the screw holes are a bit hard to locate.
  7. Reassemble the rest of the pump using your alignment marks. Note: The chopper blade is indexed with a small tab at the bottom.

I found replacement thermal switches available on ebay. Search “motor thermal switch”