The internal power assembly has two parts. There is an electric motor, which is attached by two terminals with a lead going to the power switch on the side of the electric motor piston. The vacuum pump has no electrical components. It is connected by tubing through which air flows into the pump from the machine from one side and out of the pump through the muffler on the other side.

The internal pump assembly may be damaged in several different ways. If the reservoir overflows, fluid will go into the pump via the inlet port and can damage the whole internal assembly. A power surge may damage the electric motor.

Finally, different components like the piston can simply wear out over time. So first of all, if there is no evidence of water damage and the rest of the electrical circuit is functioning, you need to test for electrical damage in the motor.

To do this first, disconnect the device from the mains. Now disconnect the live and neutral terminals of the pump. Set the multimeter to test the resistance. Touch the two probes together. You should get a reading.

Now, touch the probs to the two terminals on the motor. If you get a reading, then you have resistance, showing the motor’s electrical circuits are intact.

If you get ‘OL’ or no reading, then the circuits are damaged. If there is electrical damage, the whole pump needs to be replaced.

So first of all, disconnect the black exhaust tube from the muffler. The whole pump assembly is held in place by four screws, each with their own washer. Remove the screws and washers and put them carefully to one side.

The new pump comes with a new piston and muffler attached. Take out of the box and put the whole assembly into the device.

Put the four washers into place. Put in the screws using a Philip screwdriver and be patient. This can be quite tricky.

Now put the short tube from the muffler into the outlet on the piston casing. Attach the tube from the inlet port onto the inlet on the piston.

Next, put back the live and neutral terminals. Finally, attach the black exhaust tube back between the muffler and the outlet port.

You can now test the pump to make sure that it works. If it turns on, you can put back the blue outer casing.