Hi John,
You can back the sheet metal portion with a suitable socket, or use a scrap piece of aluminum with a hole drilled into it, and hammer out the pin. Installing a new one, or reusing the old one will require a small drift to peen over the pin's edge again to retain it in the sheet metal hole. Or you can order a set of tools just for this purpose from one of our great parts suppliers. I have had a set for years now, and they make the job much easier. Check with Steve at SNS trains, or Doug at Port Lines Hobbies. There are others, but these two come to mind right away. Or to what's left of my mind after the hectic rush of the past couple of days....
Now, there's the New Years stuff and my grandson's first birthday coming up. But it's all good!
Jerry In Wayne, MI