I heard about running a piece of waxpaper through a can-opener to keep the gears clean and moving, think it might work for machine heads? through vicarious experience, I've become bit suspicious of the tuning machines on epi's.
If these are sealed tuners, there may not be a great deal to be done with them. You can try some lubricant - very small amount of teflon - you cna get it at a bike shop - but it won't do much unless you can get to the gears. Your local music shop will be able to help you here.
Alternatively, and particularly if you like this guitar, you might want to spring for a set of Schaller tuning machines. Just check to see if the holes would require redrilling before you commit. Pull the screws on one machine, loosen the nut / bushing, and measure the hole in the head. Put it all back and don't lose any of the tiny screws. then double check the hole diameter with the Schaller specs. If they match, you can install the set yourself. If not, the holes will have to be reamed to fit, which you may not want to tackle.