Ryobi 522H Metered Dampening Ryose Recirculation Unit

Hi All

I have a Ryobi 522 that's is a very good machine, it has never let me down or broken down, it has metered dampening, new inking rollers on both units, and has been serviced in December 2014 by an independent engineer.

I am posting because when I crawl the second unit, it makes a slight squeaking noise, it does not affect the print, or the running of the machine, it only makes this noise when I crawl, I have tried cleaning the clamps, the cylinders and taken a very in depth look at the gears to see if anything is catching or scraping against them. I cannot see or find anything that is loose or hanging, I removed all the rollers (marked them first) and checked all bearings. All the rollers and bearings seem fine and in good nick, any input will be much appreciated...

Many Thanks