Whip Mix's Power Mixer Plus and the Combination Unit are the most dependable dental laboratory products in the world. So much so that I just had a customer call in for a Vac-U-Care Maintenance Kit for the unit he has been using since 1958 (and they have been on the market for many years before that!)
Eventually, after long-term use, things can start to need some attention. One of those things is a possible loss of vacuum. If that happens, follow these simple instructions and you can fix the problem within a few minutes.
First, unplug the unit from the wall outlet. To access the pump area undo the six Phillips head screws on the top of the machine and remove the end plate. This will reveal the pump area for cleaning.
Next, you will want to remove the four ‘vanes’ in the rotor and set them aside. Then take some WD40 lubricant and spray into just the pump area inside the pump body wall. Be careful not to spay down into the impellers in the top of the motor. Allow the WD40 to sit for 15 minutes (longer if the corrosion is extreme).
Next, take some fine grit sandpaper (240-400 grit will work best), and fold it so that it fits in the vane channels of the rotor. In addition to moving the sandpaper through the channel, hold the folded sandpaper down to make contact with the pump body floor. Once in contact with the floor, try to turn the rotor via the front drive chuck at the bottom of the unit. To make this easier, you can insert the drive nut of the lid and paddle assembly into the drive chuck and use the paddle as a key to more easily turn the motor shaft (REMINDER! The unit must be unplugged to do this step).
Once the corrosion is sufficiently removed, pull out the sandpaper. Spray the vanes with WD40 and scrub them. Dip the vanes in oil (VV Lubricant) and insert them into the channels of the rotor making sure the notches of the vanes face the center of the rotor. Replace the end plate securing all six screws with even pressure to avoid a gap between the end plate and pump body wall, which in itself can cause a loss in vacuum. If you are still experiencing low vacuum after this process, you may need to repeat the process and clean it more thoroughly.