Ok, got it working. Turns out that the closenode the ai was grabbing for the repair wasn't good enough. Moving the node closer solved that...seemed to work ok if I damaged the truck along the path too, so I'm wondering if the game does something strange with the entities bounding box when it's first damaged...
I also made it so the dynamite plant action on the barrier isn't activated until the truck has started moving up the hill. It required a 17th action test, so it won't work unless you are using the latest qagame in this
thread, so I'm not going to post it here. Let me know if you want it now and i'll pm a link to where you can get it.