I just read my own post and was confused myself. Let me clarify. At first with red to pin 3 and black to ground I got an increase in the duty cycle reading when turning cw on the adj screw. CW adjustment will make it richer and as a result the duty cycle reading should decrease. I the switched the polarity of the leads and observed a % increase when turning CCW (lean) and decrease in % when turning adj screw CW. Thanks to all who take the time to post replies and share their knowledge and expertise. This site is an invaluable asset to me and countless others who want to do their own work when they can and a save a few $$ in the process. Thanks again Tom