Hi Chris
I bought the prochem stair tool, but think it's too rigid and instead use the upholstery tool. I used to use two extracta hide a hose tools, but the larger of the two broke with the higher pressure. I dare say they could be modified as i used to take them apart to fix them. Just put the high pressure hose inside and upgrade the valve assembly and jet.
I have had my tm since August and you eventually find what is right for you and shortcuts. I am considering making up a whip line using my old extracta hoses as the smaller dia is easier in houses when working around furniture, and sometimes i have run a hose that is just not long enough so i have had to pull out a second hose which is annoying.
If the prochem upholstery tool was wider it would be the ideal solution for stairs but thats just my opinion. Another thing with the extracta hide a hoses was that they used to block up a lot with carpet fluff when using on stairs and they were difficult to clean out, where as the prochem one has a soft coller to open it up and a coller to disconect the solution pipe. Have you like me gone from extracta equipment to a tm. I hate using portable equipment now.
Dave