problem with neopost si 68

I have a neopost si 68 (folder, inserter, sealer). The paper seems to be off centered on the fold (right side is higher than left). Went through and cleaned everything and made sure there are no loose gears, but found a loose roller (one right before the paper goes into the envelope. I can't find anywhere to tighten it though. All the other rollers are snug. But this one moves heavily with ease. Any suggestions.