We started making time, and so did almost everyone else in the class. What I learned is that every dog does not respond to the same things, and the fix for the problem will not happen in 2 weeks. Eventually, you can try other obstacle combinations too. You are also re-training for the day you can add the lead out from the start back into your bag of tricks again. But even at that, use that lead-out sparingly.
Re-train for just running down through the contact zone.
Slow dogs will almost never blow the contact IF you signal to the ground at the end of the contact, and YOUR EYES focus down there until you see the dog hit the yellow with your peripheral vision. The biggest trick to this is not lifting your eyes or hand too soon. If you look up to find the next obstacle, or flinch, the dog may jump the contact if they are responsive at all. They are like magic to speed up your dog. Those blind crosses take lots of practice, but they actually work for slow dogs better than cross behinds, and are better than cross in fronts when the dog improves a little, but if the dog is still in that medium speed zone.