Killy's A-Frame

I have had issues on and off since last fall with Killy missing his down contact on his A-frame. He has a 4 on the floor and up until fall it was solid. I tried to figure out what was causing the problem-was he too excited at trials? Was I not driving forward enough and his head was coming up causing him to leap over the yellow? Was he reinforced to much for the bottom behavior causing him to leap over the yellow?

Well, I think I found the cause today. Last fall our A-Frame developed a small hole when one of the nails holding the slats in place came out. My solution until my husband fixed it, was to take a piece of duct tape and put it across the A-frame where the slat was. We used the frame all fall and winter (we had a nice winter). Today I was working some a-frame tunnel discriminations so I was primarily using the down side with the duct tape on and I noticed something...each time his front feet hit the tape-he leapt! I ran him the other way...no duct tape and he ran down entire side beautifully, just like he was taught. Ran the other way again w/duct tape....leap. Hmmmm....I think he has picked up the tape as a cue. Not sure why he is doing it in a trial though, but I think I figured out why he is doing it at home.