first off , throw that damn rubber renew away, it will totally screw the feed tires and make them brittle. I use GooGone as it isn't as hard on the rollers. Also make sure that the rollers after the feed rollers are clean(access from the bottom of the adu. If you have used rubber renew on these, they are probably screwed. The rollers in a copier are not the same as a press
GooGone Goo Gone 4oz Bottle
There is an adjustment for the seperation roller pressure , if you increase the pressure it will help a little( 2 brackets thet the seperation springs attach. Then go to a hobby shop and ask for dubro stick on weights for balancing rc airplanes or a tire shop for stick on tire weights and add about 1/4 to 1/2 oz on the top of the take up rollor frame to give more pressure on the take up roller. You may have to adjust the spring pressure that is used to raise the feed roller back up(its the screw in the slotted hole to the rear of the tire assembly)
Also make sure of the grain of the stock, it should be flexable in the feed direction. If you are getting cut then make sure that its the right direction. Give the machine a fighting chance(we went through hell on one account only to find that it was the wrong direction)