Hello Dom G
I just Did the same job on my S1. took me a little to figure it out also, The way I did it was to loosen the crosshaft coupler and lift the headlight up so that I could get my hand in there. I used a 1/4 inch socket wrench to loosen the bolts.
Hope that helps.
BTW , What faild on the original motor? Mine was the nylon gear inside. I was able to have a local machinshop make me a new one so I didnt have to by a new/used one.
Dave