I’m working on cleaning up an SP15 that hasn’t been touched in maybe 30 years. I have all the rollers lubricated and in their right places (as far as I can tell) but when rolling the carriage down the press bed, the rider roller isn’t moving. It almost seems as though it’s a hair too wide to fit into the u-shaped cutouts in which it sits, and thus it doesn’t move freely. Any ideas? I’ve tried adjusting the heights of the form rollers and using different lubricants in the u-shaped cutouts, but to no avail.