The original tensioner block (shown in the image as the wooden piece sitting on the bed) with the two wooden hand-adjust screws had some major issues, including dragging on the belt and chipping off chunks of wood to fall in my prints. The new one gives a much greater range of tightening and doesn't risk damaging your belt to the point of it wearing right through!Print this, then you will need to use a small file on the belt slot to get it through and have enough room to loop it back around the printed pin. A piece of 1.75mm filament would work just as well.