Thanks for all the suggestions on the Head removal.
I removed the screw plug on the tensioner with a 7/16" allen wrench and pulled out the spring.

Now I'm trying to take out the ring nut. It looks like a 12 point socket.
What size tool or allen wrench do I need to take that out?

P.S. Thanks for the tip on the 6mm bolt and 10mm nut for the guide rail pin. I think I understand that the you screw the bolt into the pin and the nut acts like a spacer to pull out the retaining pin.

Thanks again for anny suggestions.
Mike v

It's been awhile since I did this, but it seems like I used a 12MM, 14MM and 17MM hexhead sockets, it took several sizes. It would be a good investment to have all these sizes in your toolbox.

I'm sorry I don't remember which was which.

Good luck,