You dont say what your problem is with the finish using the Sensai, nor what method you use, nor what products.
Can you give more detail.
Also, whilst a hot water machine is pretty much a standard, it might not be the best for the use you putting it to ie office carpet.
Many carpet cleaners also use a rotary machine with carpet cleaning pads. Far quicker then with hot water extraction, probably cheaper to buy, and still achieves a good result.