+1 the knife needs to be one solid piece. Either welded in, or made in. Yea, a pain to sharpen but a good file or stone will do that. Think if something like the sickle in the horror movies. Sharp tip, and a long curved cutting bade. And they can be very sharp.
brino I can see that, but the hook on the opposite side to pull the carpet up with. This way you can pull it up a little cut into chunks and pull them out of the way without having to get down in the muck
If you grind a thin slot into the hook on your tool, so that the end of your blade fits into the slot, it should prevent the jamming you are getting. Then the blade is still replaceable as you have designed.
Use your hook to pull it off the tack strip and over on top of itself than cut through the backing. When I strip carpet I go with 3' wide strips rolled up and stacked at the curb. Here in Florida the carpet company's pay for the old padding ...not much but better than throwing it away... **G**