I recently picked up an older E-6B marked "Weems System of Navigation (A Division of Jeppesen & Co)". Even after a thorough cleaning, the calculation side does not rotate as easily as I would like. If you happen to have a manual, are there any suggestions for lubrication in it? It is identical to the one advertised here: http://cgi.ebay.com/Aviation-Airplane-WEEMS-E-6B-COMPUTER-Case-Instructions_W0QQitemZ5851013583QQcategoryZ84077QQssPageNameZWD1VQQrdZ1QQcmdZViewItem Several have suggested oil, silicone spray, etc. but if the maker suggests something, I would feel safer using it.