After cleaning, the replacement lubricant needs to have the same long-lived and benign qualities of white lithium grease. However, if you are relying upon the bearing to provide electrical continuity between the capacitor shaft and the frame of the capacitor, the lubricant should be electrically conductive. Such products exist. Some of these use powdered graphite, or metals (maybe even silver). "Anti-Seize" (manufactured by the STL Compound Corp., Lombard, IL, tel. 630.953-1515) contains both powdered nickel and graphite; it is designed to prevent corrosion, galling and seizure in external environments. These it does admirably, but I have yet to verify its electrical conductivity with an Ohmmeter.

If the capacitor is not going to undergo vigorous rotation, e.g., when driven through a speed reducer or vernier drive, an electrical connection more effective than that of any wiping contact can be achieved by drilling a small hole radially into the rotor shaft, and then soldering a piece of braided phosphor bronze wire between that hole and the capacitor frame.

The most important point is not to let any of these high-powered cleaning solvents make contact with unglazed ceramic material. Indeed, most ceramic used in rotary switches, roller inductors and variable capacitors is unglazed. Such ceramic is porous and hygroscopic. To attenuate its moisture absorption, it usually has been impregnated with wax. Even mild soap and water, not to mention heavy duty solvents, will remove the wax, thus degrading high-grade ceramic insulation to the point where it is electrically little better than a wet noodle. To clean unglazed ceramic insulation, go no further than rubbing it with a soft pencil eraser.