I've just read on another site that courgettes produce both male and female flowers, that the male ones tend to appear first, followed by the female ones, which are smaller. Fruiting can be aided by making sure the male flowers connect with the female ones, so a little bit of interference or assistance with pollination between the two might help.This process was not described in detail. And that's the full extent of my knowledge on this subject, not being a veggie person really, lol

Aha ! like 'tickling' with a paint brush as I did for my tomatoes .... Val