Hi all! Our studio has had a Shimpo SR-3050 slab roller for a few years now, and generally no issues. However, this week we've noticed the black hand cranks that adjust the height of the rollers seem to be a little sticky (and squeaky), and today they gradually stopped turning altogether. I attempted to grease (machinery lubricant, not WD-40) the chains and the threaded rods that are attached to the cranks, but still very little movement happening. I've also tried tightening and loosening the chain in case it was jammed or caught--no luck. Has anyone had a similar issue? First time posting so any advice is welcome!