Hi Edmund,
IF you have not found this already, try: http://mirror2.ipdb.org/files/2252/Bally_1980_Space_Invaders_Manual.pdf
Sometimes they can be hard to see depending on who scanned them.
My guess is after the weekend there will be more people on the site to help you!
I am off to work or I would try to help you sort it!
Good luck.
Milton