There are 7 steps to be followed in plugging up a bombe as follows.
(1) Obtain menu.
(2) Number-up menu to reduce number of commons used.
(2a) plug commoning plug into enigma jacks
(3) Plug enigmas to commons.
(4) Patch commons to diagonal board, also patch input.
(5) Count the letters plugged on the diagonal board and compare
this count with the menu.
(6) Count the number of plugs in the commons. Never should be
less than 3. Compare this result between banks.
(7) Compare commoning jack positions in enigmas between