Yes, the leadscrew is sitting on a lock collar, which is resting on the bearing. I would really like to come up with a way to hold the bearing and leadscrew in place better. There's no problem during normal operation, but if, for some reason, the bed tries to lower below it's max limit, it can pull the leadscrew or bearing out of the holder. Doesn't happen often, but it has happened a couple of times. I'm going to add a z-max endstop to prevent it from happening at all. I've added a picture showing the detail.