Hmmm... I adjusted some of the first Ascension's, both 1k and 2k, but that was a loooong time ago. First, I don't know about this "learning the hoistway" that you're describing. Forget about that and move on. I don't recall the down direction limit affecting DN and DNX.

The U.S. micros of that period would continue to level down if they got below the LU. The most probable cause of your problem is that the elevator is blowing past the floor. I'd first make sure that the tape reader is seeing the STD, and the step down circuit is functioning properly. Also make sure that the valve is adjusted with 3-6 inches of leveling into the floor. Don't try to bring it in hot. Also, it's possible that the LU circuit is not functioning properly. As the car sinks below the floor, if it doesn't get the LU, it will just keep sinking until it's out of DZ, then start recovering down. That's all I can think of right now.