I have read in the manual that one should periodically wipe accumulated dirt from the antenna. I am concerned that by wiping I will be removing the lubricating grease and will end up messing up the antenna. These things are notoriously problematic. If I wanted to clean and then lubricate the antenna what kind of grease would I use? I once tried WD40 on one of these and it totally degreased and messed up the antenna so that it would not go down all the way down.