OK, I put the "new" crankset (the Acera that replaced the CT-90) back on, tweaked some derailleur settings, and tomorrow, I will take a long ride to see if this solves the problem. I had decided to eat this crankset after I installed it and started experiencing problems with chain rubbing and bad shifting. I think re-positioning the derailleur and re-setting the limit screws may have resolved these issues. I will keep you informed, as I know the status of my fifty-dollar crankset and quarter-century-year-old bike are going to weigh heavily on you all for the next 24 hours.