You guys may laugh, but I vaguely remember a similar case many years ago and the best "lubricant" was solid soap or wax, I just can't remember very well which one it was, I was a kid at that time. It was what tailors used in older days in Europe to make their marks when they were making a custom suit on somebody. I must have been 5-6 years old, and it was a credenza with rolling slats that were not moving easy. That solved the problem.