Looking great Andy, I'm also working on an antweight 4-bar lifter (very much languishing in work-in-progress CAD though).

Do you have a way to stop the motor when the lifter gets to the end of its travel? I was planning on using a servo to stop it damaging itself, but it doesn't seem like a great power-to-weight ratio whereas that is super fast, looks more like a flipper than a lifter.