Yeah, I forgot about that one too - and it just happened to me a month ago!
It was a virtually new 6x4.5 Hassy back and the interlock mechanism in the back went haywire. Loaded a roll of Efke 25 and lined up the arrow the way you are supposed to, closed up the back and started cranking. Went all the way thru the roll without realizing something was wrong!
After a $100 trip to the Hassy repairman all was well again!