So I was trying out new Dreher macon oars last Sunday and once on the water I could not believe that I could not feather and square my oars as usual. I immediately thought that somehow the oar sleeves were improperly installed on the oars. After much back and forth with Durham Boat Company, the manufacturer, I found that the problem was a tiny bolt that sits on the rigger gate. That little bolt can be adjusted to tighten or loosen the gate around the oar sleeve and makes all the difference in rowing normally.
Just FYI when you buy new oars (almost never!).