May not be the safest, but I could see putting the whole meter in a 5 gal bucket with lid and shaking it with your mix of degreaser / water like an improvised washing machine. Periodically you could activate the mechanisms to loosen and rinse away debris and contaminants. When you're done you dry it with compressed air then strategically spray white lithium grease with an extension hose/tip in each gear and wear point. The only party concerning is any weak parts that are made of aged plastic etc... I agree on not taking it apart, that'd be like trying to rebuild your own Swiss watch even though it still ticks.
