I always have a hard time explaining my idea behind the mini-mat.
If you've ever taken apart your stackmat, you'll see that the circuit board inside is only 1/3rd of the whole stackmat.
You can sufficiently remove the board and use the sensors raw (they're little rubber things on the right and left, they work exactly the same as the palm inputs to. You'd be using only 1 finger on each hand to activate the sensors, but it actually works pretty well and they're more sensitive raw than they are on the palm mats.
If I get another stackmat I might demonstrate this further, but for now I want to keep the one I have in one piece. I hope this all makes sense, oh, and if the board still doesn't work raw, then you just have a really faulty stackmat.