I purchased this product to make upholstered cornices ( I attach decorator fabric to wood boxes made from 1/4" plywood and 1" pine boards). My electric and hand held staplers did not have the force to penetrate the plywood. Now, with this product, the force of the staple puts holes in the cardboard tack strip. I lowered the pressure to 60 psi, but the force is still too much. Is there another way to adjust the force? Am I pressing down too hard on the WCE? Any other advice?