Just when I thought I'd stumped Sheldon's vast catalog of knowledge. This was helpful. It seems that the spacing is indeed my issue. Does anyone know if the spacers are built onto the cogs or if they are separate (therefore spacers can be replaced independent of the cogs.) I haven't torn it down yet as our bike co-op does not at the moment have any chain whips available and I'm too poor or stingy to buy my own yet. Sunday I plan to have access to a chain whip, and I already have a vice and an old chain to use as the second chain whip.