Ray what I did was use a open ended spanner and ratchet when undoing the bolts and the roller was in situ.so I assumed which was wrong that I would put it back together the way it was undone. BUT does not work like that as I have found. so I now have some different ways to tackle the job and now I think it will go back with ease.
You’re half way there, stick a bit of card under your open end, place the nut on it, push it into the jaws and slide it under the engine. Probably easier if you can get the machine off the ground so that you’re not bent double.