Well I tested all the tracks on the circuit board and all measured 0.00ohms. Everything does look ok...so had another look at cogs etc and I found this...the missing cog! On the end of my finger.. Same colour as the old small cog. It was jammed in amongst the other cogs....I just wonder if this was stopping something!!!!
Will put it back together and go for another drive! Fingers crossed, again!! Lol