Windshield and flywheel questions..

Morning all.. or most.. ok, some..

        I am trying to figure out how to install a new windshield (winscreen)  
seal in the bugeye.  I see no way to get it in between the frame.

Also, the ring gear on my flywheel looks a little rough and I would 
like to purchase one of those as well BUT I have never replaced one.  
How tough is it to do?

Thanks all!

Lester