Do you have a friend that's an electronic wiz? If so, get him to modify one of the little 100W inverters for use as a drive corrector. Tell him that you want to control the 60hz frequency with an external pot so you can set it to 60hz exactly (driving the RA at the right speed so the star doesn't move) and that you want a button so that the frequency will go up to 100hz and down to 40hz depending upon which button (use buttons rather than a toggle switch which will break off when you put it away) you hit. He should be able to find the 1 resistor that fits the bill for this. I have done the mods to several different inverters and have several here at home if you really want me to, I can convert one for you for $75 - inverter included.