If that retaining pin is anything like the moss 500 it is a pain to drift out. Be absolutely sure to use the proper size punch and a piece of wood to set the bolt assembly on. You will have to drive it fairly hard.
I had the light strike problem a couple years ago. The cleaning like Clark said worked for a while. I thought mine needed a new pin so I took it apart, all it needed was a good cleaning, light oil and reassemble. Been fine the last 2 years.