Walther WSR 160 problems

From: Robin F.


I have a Walther WSR 160 mechanical calculator (known as a Mendivo Mentor in the UK), which has an annoying problem: lever no. 8 is very hard to move. It works all right, but moving it requires much more force than the other levers, and it often gives problems with the gears skipping a number, causing an offset. What can I do about this? Clean, lubricate, or just live with it?