My model is the 7901 so it may not be the same as yours. On my model the water flows from the tank to the auto-mix assembly (detergent dispenser) to the pump and from the pump to either the wand or the main nozzles (via the handle where the heater and control valve are located.)
Assuming your belt is not loose and the pump is spinning properly first check to see if you have flow out the wand. If the pump is working and water is getting to the pump and the valve in the wand is working you should get flow out of the wand. If this is working then the problem is in the main delivery system after the pump. First check to ensure your nozzles are clear of debris. Then check that the flow indicator (spinner) is sealed properly and that it is not clogged. Soap and other particles build up and plug the very small holes that the water has to flow through. If these are clear then you may have to remove the casing to access the other lines. If yours has a heater core often soap buildup and corrosion occurs in the heater core and it will need to be disassembled and cleaned out. On mine, the valve in the handle also had some buildup which made it difficult to press and release. I had to soak and manipulate it to remove the buildup. Some of the lines can also clog over time or may even deteriorate to the point that you might have to replace some of these with new tubing. The nozzles may also be clogged internally. In this case they will need to be removed and air or water can be forced through to remove any material clogging them. The screw in the base method remedies the problem of the valve in the main tank not releasing water when it is placed in the machine. The screw pushes the valve up if the existing plastic piece in the base is not long enough or possibly the valve is just sticking and needs some extra force to make it release. You can test the valve by holding the canister over a sink and pushing it up with your finger. Water should freely flow out of the bladder. The machine case is relatively easy to remove but takes some care and patience. There are only 6 Phillips screws holding it down (2 at the back wheels, 2 on the inside where the water canister sits and 2 at the front outer corners holding the clear plastic face cover in place.) other than these, you will also need to remove the flow indicator lid, as well as the detergent canister, and while lifting straight up (gently) turn the auto-mix knob back and forth carefully so the valve will slide up from its casing in the auto-mix assembly. Putting it back together is the reverse but the hardest part is ensuring the auto-mix valve is inserted into the opening properly. It is very hard to see what you are doing because the case covers this. If the auto-mix valve is dry it will not slide very well so you might try lubricating it slightly with some petroleum jelly. There are a lot of videos online showing how to disassemble the machines.
Kim, January 2017
