Thank you, we have been in a round pen that is enclosed. It kind of makes me wonder if her "bad" side was traumatized in some way?
I may be pushing her too fast... And now that I think of it, I always had her stop AFTER she began her pulling....
You're right, I need to catch the act before it happens and escalates to that..... I know this.... I just have blank minded dum moments.....
Horses are normally "bad" on their non dominate side, and that's usually the right side. I doubt she's been traumatized.
That being said, if she's having that much trouble (and inadvertently been reinforced to do so), you need to go back to square one with her.
Instead of insisting she's going to lunge right...and before you do any more lunging at all...start her all over again from a stand still. First work her left side and get her to flex to you, yield her hind quarters AND her forequarters, and get her to back up. This is her dominant and better side, so start there.
Once she's doing this perfectly on cue, THEN move to her right side and repeat. This is going to take some time and patience most likely, but do not move on to anything else until she has these basic steps mastered on both sides. Start with one movement such as yielding her forequarters and do not move on to the next thing until she does this every time you ask. Then move on to her hindquarters, etc...
If she's having particular difficulty on her right side, go back and have her go through the movements once on her left side, PRAISE her, and go back to the right side. Praise every single movement she does correctly and remove all pressure at the slightest (honest) try she gives you. Then repeat, up the pressure if you have to, then release it when she gives in to you.
Once she does these maneuvers at the stand still perfectly, THEN you can go back to longing her. It's all about baby steps, feel and timing, and releasing pressure at the precise moment she tries for you. Make the wrong decision hard and the right decision easy.