I've started to disassemble, clean the contacts, lube with dielectric grease and reassemble many of the OE switches on my rides because a lot of the aftermarket stuff is junk. If the original is available and not working you have nothing to lose, and maybe can learn a new skill. Most stuff will have springs, detent balls, etc in them so I usually hold them together in a vise or some other means while I pry open any bent over tabs holding things together, then release the part slow so stuff doesn't go flying all over the place. I have cleaned up dimmer switches in headlight switches, heater fan switches and later key switches. I'd bet your new switch has an issue with whatever detent mechanism is built into it not working or not pushing hard enough so that you don't feel each position of the key. It may be that whatever spring is responsible for the detent feel isn't pushing hard enough. Maybe the check ball is missing from the factory.