How can I fix the drawing ability of my curtain tracks?

Have just installed drawstring curtain tracks which were DIY and already set up. Followed the instructions and the mechanism worked great. Hung the curtains and now one side stops part way when opening. It can be manually pulled back and doesn't have a cord hanging down. Installed the next track and decided to change to left-hand draw. Followed the instructions and when opening, the right-hand side curtain now opens across three quarters of the window (opposite problem to the first track.) Help!