Welcome to GTT
from a fellow Brit in Devon; you have certainly come to the right place for info. I saw that on eBay and I am really pleased that it gone to someone who will rejuvenate this little tractor. You got it for a very good price if I remember rightly.
Get some photos up so that more experienced and knowledgeable guys on here can help you.
Regarding your rear wheels, I don't know if the 650 got a cottor pin that you need to 'pull out' the free wheeling pin on the rear axle behind the right wheel? Very difficult to see from the photos that Iain posted if there is a differential knob on the outside rear wheel that you need to undo. I could be wrong about this, if so someone will chip in their views.
Be great to have a thread to follow on the 650.
Best of luck.
Edited by Bolens800uk, December 10, 2015 - 12:40 PM.