Switching Gears on your 2-Speed Bluerock 4Z1 concrete core drill gearbox high and low speed settings

The 4Z1 has a 2-speed gear box with straight cut gears which are designed to be stronger but can be harder to engage and need to be perfectly aligned before they will slip into gear. This can be done by rotating the bit by hand until you find a spot it engages, or engage the throttle while turning the gear selector knob as the drill is slowing down. Do not force the gear selector with pliers as it can break. It helps to apply pressure by hand to the gear selector knob while turning the threaded drill spindle, until you can feel it slip into gear and the selector fully locks in gear.