Hi @alex44,
Welcome to the Bunnings Workshop community, it is wonderful to have you with us.
When drilling into masonry, your drill is under heavy load, so jams are possible and fairly common.
The first step is to make sure the drill is completely powered off by unplugging it or removing the battery. This prevents any accidental activation while you work on freeing it. The jam is often caused by dust or debris getting into the chuck or gears, or by the bit binding tightly in the jaws after heavy drilling.
Try spraying a bit of WD-40 into the chuck, then allowing it to sit for 10 minutes. After 10 minutes, grip the chuck tightly and rotate it. A strap wrench or even a piece of rough cloth around the outer sleeve of the chuck could help give you more grip if necessary.
If this doesn't work, striking the head of the masonry bit while rotating the chuck can also help to jolt the mechanism free, so striking the bit with a hammer or on a hard surface can help.
Once the bit is free, the chuck should be able to rotate freely, and the jammed selector should be able to rotate more freely because of this. If there are any issues, try gently rotating the chuck and then rotating the selector as there could be a slight misalignment of the gears.
Give this a try and let me know how you go, happy to help further if required.
Jacob
