Check this neat stretcher out especially good for us old guys with battle wounded knees. http://meitools.com/
Messed around with the compressed air version. It wasn't the best to be honest. Also a large gripper gap is needed. In the demo videos the carpet is not hooked on the opposite wall. Trust me it dont stretch like that when put under pressure. Still, not tried the electric version. I will see if i can hold of one to see if its a improvement.
You can do the same thing with the Roberts double headed / seam stretcher. It comes with a flat plate that you can fit on instead of one of the heads, then use it the same as the electric and air versions.
