Our police cab didn't have the modification Dave, that is why you didn't see it!
If you carry out a start and it fails to light up, the starter motor cuts out, winds down and then at a specified rpm it attempts a restart. Can't give you the mod details because I can't be arsed looking!
Your later aircraft may have had the mod, but it never failed to start. We went through a month of this happening regularly, I have only seen it once recently