Why is Fellowes DM8C Paper Shredder Jamming?

When I look into the feed slot, I can see paper jammed in the cutting cylinders. I’ve removed the lid and cleaned out every bit of paper from the cutting cylinders multiple times (no easy task). But shortly after doing so, the shredder jams again. I’ve oiled the cutting cylinders, which used to help. But now the shredder will only accept about 1” of paper before jamming again. I read the comments here on a different Fellowes model, but they don’t apply to my situation. On principle, I’d prefer to try and fix the problem rather than buy a new shredder; however, I don’t want to spend more on a replacement part than I would on a new shredder. Any suggestions would be helpful.