We have one similar to this with some extra (and pointless) hoses
One thing I did notice is that sometimes the soap doesn't come out for a few minutes even when it's switched on. Have you noticed whether the water being sucked back into the bottom of the machine is sudsy? If not, you might need to try switching the soap button off for a moment then on again. Also for very stained carpets it can take quite a few "passes" to lift the stains.
CT I wonder if the soap is dispensing properly? Can you smell the detergent smell when the machine is cleaning? Have you checked the little black hose on the soap compartment is connected? Thinking off the top of my head here The last time I used ours it took about 5 minutes for the soap to start coming through although I have no idea why
Right, it is all dry now and I do have to admit some of it is cleaner. I have a clean patch where I tried the a particularly dirty bit in my offie, so I guess I'm just going to have to do them a few times until they get clean.