I created this model to more precisely align the bed the machinist way. The model attaches to the tool head just like the fan cover using magnets. Before attaching to the tool head I recommend powering off the unit before disconnecting and reconnecting the fan plug. The three 4X4MM magnets are press fit they should slide in easy and be snug. The indicator is secured by a ¼ 20 X 7/8 socket cap screw. The threads are a little snug but you should be able to tighten it down fully if not you can tap it with a ¼ 20 tap.

The way I aligned the bed is I moved the bed about an inch away from the nozzle then disconnected the power and remove the cover and the fan plug. Keep in mind which direction the plug goes or else the fan will not work until it is flipped the correct way. The attach the new cover and by hand move the tool head across the bed adjusting the bed as needed.