Hello and welcome to the board, and congrats on the find.
Steering wheel can stay on, BUT the airbag has to be removed. Its no fun having explosives resting on your lap.
In the on/off switch the rod that supports a tiny sprocket most of the times breaks and hence to locking of the button.
Not really feasible to repair as the rod and sprocket are tiny plastic pieces.
Look for a replacement, or use the dime