Hi Goldy, my A10 has a leak from the rockerbox which I'll do over the winter. The oil spots after a ride ,are the same as yours, chaincase,in the dip of the timing cover ,on magneto and round the fins.When run in shed just runs down fins . Check also the rocker feed connections,fibre/special washers even the feed pipe may have a leak, could be something as simple as this,hope so regards BobH.