A quick thought, are all your tuners stiff? If it's only some the cause of stiffness could be the keys have been bashed so that the key-post might be slightly bent thereby rubbing their keepers excessively. I have this problem with one of my vintage basses- have removed the offending tuner and tried straightening in an engineer's vice with limited results (without damaging it further!). Either way I do oil the machines once in a while, I'm ashamed to write this but use motor oil, even grease in the ferrules. There isn't any evidence of damage to the EBs, T'birds or Jazz finish.
Roger Phillips, Kendal