I couldn't resist, a 12" Fowler dial caliper at a yard sale for very little money. It looked to be in nice shape but I didn't check it out thoroughly before handing my money over. It has a small problem in that it does not always return to zero when it is closed. I varies about .004" - sometime it goes past by .001' and sometimes it indicates .003" shy of being at zero. Sometimes it is right on. I did find some buggers or something on the rack gear Which I cleaned off with a pin and figure there must be more on the pinion. The stuff is very gooey. I took the four small philips head screws out and the two set screws for the friction device but the dial and mounting plate would not come off. What am I missing? Or is it glued in place with the buggers? I got a pile of stuff with it and it was essentially free so no big loss if I can't fix it.