You indicated that you "have to push" the wood. That tells me a couple things. One that your tension is not high enough, two, that you are cutting with a dull blade, upside down blade, or even the blade is in backwards. Been there, done that myself. Another reason might be that you are trying to cut too fast. It is better to use a higher speed (strokes per minute), higher tension and let the blade do the cutting by not feeding too fast.