Odd behaviour from my Shapeoko 3

Cutting a slot just as narrow as the endmill is wide results in near constant 100% tooling engagement — best practice is to add geometry around the outer profile by offsetting to the outside and cutting as a pocket down to tab depth or the penultimate pass:

For the BitSetter issue, check if the button rotates freely — if it does, measure the height, then rotate it clockwise a couple of times, then measure it — is it different in height? Repeat, but rotate counter-clockwise. If the height changes at all, contact us at support@carbide3d.com and we’ll arrange to rebuild it.

If the button checks out, please make sure that you are always using the interface for every tool change — if you still have this difficulty send a .c2d file, generated G-Code, and step-by-step notes on how you are securing your stock and setting zero relative to it to support@carbide3d.com and we’ll do our best to look into this.