Today, while cycling through my Conrail locos with 5 minute runs my RS-2 started clicking. It's a 20 year old Kato that was my first (and only) paint job. Right away I thought of the split gear problem. You know, a plastic gear on the metal truck shaft splits throwing the gear pitch out of whack causing click, click, click.
I took off the shell, loosened the frame screws and dropped both trucks. One truck rolled free but the other was "frozen". A close inspection revealed no split gears. Instead it was a compacted fuzz ball wedged down in one tooth root of the small gear attached to the worm gear. I picked it out and the truck rolled freely.
Reassembled and no more clicking.
This is a first for me: fuzz ball attacks RS-2.
Conrad