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As you already know, the camera does its automatic end-of-roll wind after 16 or 33 actuations depending on whether a 120 or 220 holder is detected. Therein lies your clue. If you have been having this problem with a properly converted 220 holder, you should not have been. The detection mechanism in the camera is probably malfunctioning. You may also be having frame spacing problems.
Steve
P.S. The educated opinion exists that using a 220 holder with 120 film has potential to overwork the film advance motor due to excess pressure plate thickness.
Last edited by stevebrot; 06-01-2019 at 06:12 PM.
Reason: completeness