I had mine lockup once, used the tool to release it, and haven't had an issue since. I wonder if it thinks it's still malfunctioning? Maybe there's a sensor issue with the car not thinking it's in Park? I know you can pull the lever while in drive and activate the break, but it won't hold once you release it if it's in Drive (learned that hooking up the boat last summer). Maybe it's not seeing it in park?