Boomer hasn't had a 'pulling' back incident since we brought him home from the trainer about 16 months ago. He did have two incidents where he dropped and panicked in cross-ties, but not pulling back.
I still do not trust him and would never consider him 'cured'. I always treat him as if he can and will pull back. He still wears his 'Be-Nice' halter and is always tied fast with a cotton rope and bull snap.
Today I was grooming him and he raised his head while I was spraying his mane with detangler, so I pulled on the lead rope to get him to drop his head and he resisted, so I held pressure strong while I continued spraying. He pulled back and struggled. I saw that the rope would hold and I took a step back so that I was behind the line of his shoulder and shouted at him to 'GET UP'! He stopped pulling, stepped forward, dropped his head and started licking. I gave him a second to deflate, then I approached him and rubbed his forehead.
I decided to go get the clicker and a pocket full of treats and do a little training session. I retied his leadrope to make sure it was still secure. I approached him and started to apply pressure to the leadrope, he immediately pulled back again before I could even start spraying him. I stepped back and shouted at him to 'GET UP'! He stopped pulling and as soon as he dropped his head and started licking his lips, I clicked the clicker and gave him a treat.
Next time, I started spraying him first, then gave him a click/treat without pulling on the rope. Then I sprayed and pulled on the leadrope. He stepped forward, but didn't drop his head- click/treat. We did this a few more times and eventually he would let me spray him without raising his head. Same reaction on the other side. I was very happy with this.
I think in the past when he pulled back, it really freaked me out and I would untie him right away and then baby him about whatever had freaked him out. Today, my reaction was different. I approached the situation by pushing his buttons and TRYING to get him to react. It was HIS decision to stop pulling back. I was there to reward, but I didn't try to make things easier or more comfortable for him. All in all, I think it was a good lesson for both of us.