For those who have laptops with any diagnostic translators you can down load bendix diagnostics for free. You will need this if you have 2016 bluebirds, not sure about IC or Thomas newer buses, but the flasher looking tool does not work with them. Below is the link.
I don't have anything for hydraulic brakes. If you haven't already, I would look for sight holes where you can inspect the tone rings, check for obvious wiring/ sensor damage and make sure the wheel sensors are pushed in till contact is made.