It's important to learn and know how the game features an odds operates, including the Red Letter game and Magic Screen.

Make sure there are 8 balls in the game at all times.

This link below is really helpful and will help learn about the internals of the game and how they work.

http://www.pinballcollectorsresource.com/russ_files/inside.html

There were many reproduction Bally bingo back glasses made for lots of the Bally bingo games from all years of manufacturing, especially the 1959, 1961 and 1962 Bally six cards games like 1959 Lotta Fun, Barrel -o- Fun, Barrel -o-Fun 61', Barrel-o-Fun 62', 1961 Lite a Lines, Fun Spot, Fun Spot 61', 62' and 63.

These reproduction back glasses who ever manufactured them never put the shiny mirror edge trim on the back glasses, which is a dead give away that they were not originals.

I remember about 20 years ago i went to an operators warehouse in PA that had about 75 bingo's in there and almost ever game had a repro or homemade back glasses in the games. They were mostly early 1960's and 1970's six card games. It was the coldest day of the winter at about 5 degrees outside and colder in the warehouse.