Quote from M-62A
” The “Distributor set at No.1” presumably relates to the brass wheel on right hand side of the sixteen switch unit – referred to as the “drum switch” in the Fig 24 I posted.”

Looking at one I have the drum switch when turned changes the function of the unit as indicated by text in the clear panel. The options are ‘Container’, ‘Distributor’, ‘Single and Salvo’ and ‘Safe except for jettison’

However mine is connected to a thing called a Distributor Unit Type VII 5D/1065 which is a clockwork contraption used to regulate the spacing between bombs by changing the time delay between release of each one (I presume). This distributor can be set on any number between 1 and 32 and is operated by turning a pointer to that number and then pressing a button which lets it turn back to the start, as it does so it makes contact with different terminals presumably letting electricity flow to each bomb release shackle.

I hope that helps.
Paul