The SimpleHuman automatic soap dispenser is a touch-free pump that puts soap or sanitizer in your hand when you place it under the sensor. These are great in dispensing soap without having to touch anything but over time the soap can dry out (or if you use too thick a soap) and form a blockage in the tube leading from the pump to the dispenser port.
If this happens, the pump will whine but not dispense any soap. Sometimes you can flush it with water or thinner soap but if the blockage is too thick the only way to fix the problem is to disassemble the pump and remove the blockage.
Step 1: Remove 3 Screws
The bottom is held on by three screws: the battery compartment screw (which is the one you normally use to replace the batteries) and two pump compartment screws.
Step 2: Remove the Bottom
Remove the bottom of the dispenser.
The dial has a small cross bar that fits into the slot in the potentiometer. Note the location of the slot and the potentiometer. If you accidentally change either of them your pump will have different settings and you will need to open it up and adjust it. Also, when you try to put the bottom back on, you will need to ensure the bar and the slot are in alignment or you won't be able to attach the bottom.
I had already removed the pully before I took the photo.
Step 3: Remove the Pully and the Pump
Remove the pully from the motor and the pump.
Unscrew the 4 small screws that hold the pump to the assembly. The pump is not symmetrical so it needs to go back in the same way but it really only fits one way.
Unhook the pump from the flexible plastic tube. The tube feeds the port at the top of the dispenser.
Step 4: Remove the Electronic Board
To get easier access to the pump tube, remove the two screws holding the electronic board and base. The board should just pull out.
Step 5: Clean the Tube
This is what we've been waiting for and is the most difficult step. You need to clean out the hardened (or thickened) soap that's clogging the tube.
What I found worked best was a long and thin plastic rod that I had (a Camelbak cleaning rod -- just the rod, not the brush). Camelbak has changed their cleaning kits so unless you have an older one what you need is something long but tiny that will fit down the tube and break up the soap.
Also what worked especially well once I broke up some of the soap clogs was a Sawyer Mini cleaning plunger (syringe). It's the perfect size for the tube and allows you to force the water through it. You might try a SmartWater bottle with the sports cap but it may be too big for the tube.
Step 6: Marvel at the Pump
The pump is pretty interesting and should be fine but it's interesting to see how it's constructed. What you see in the photos is the pump face that fits on the bottom of the soap reservoir and is fed from the tiny hole in the top.
The top of the pump is not glued and is just resting on the pump. I discovered this when it accidentally fell off.
Step 7: Reassemble the Pump
Put everything back together and you're done.
Remember to align the dial and potentiometer.
If you want to check to see if you've fixed the pump before putting it all back together, note that you can put the battery compartment back on without the bottom (but you will need to remove it when you attach the bottom).
I had some problem testing the pump with just water but once I put soap in the dispenser it started working just fine.