The original sprocket and part of the tubular shaft, both too large in diameter, were cut from the clutch housing. This was extended with a correct length and diameter replacement which was a VERY tight push in fit. For push in I should say helped with a hammer. This was drilled for a roll pin as was the replacement sprocket. Although the other end looked like it would never move this was also drilled and pinned while I was at it.
The gearbox sprocket was not in line with it's big brother on the axle. It needed to be moved inwards about 1/4". A slice was carefully cut off with a thin cutting disc in my Dremel, held as steady as possible as these discs break almost by looking at them. I got almost all the way through before the disc mounting shaft bottomed out. The last bit was done from the opposite side. No photo's of this operation but before and after shots with the sprocket back on the gearbox. The section cut off, first photo, now moved to the outside.