The switch appears to have been replaced with a switch from a different radio; the shaft has a flat side referred to as a 'D' Shaft. Don't try to forcibly remove it, more damage could result. If you have no luck figuring it out and don't have a local repair shop to take it to, I'd be glad to look at it for you, no charge. If so, just send me a PM and I will give you my information.
All the best.
Ray