My G-III QL/17 seems to have a problem with its film advance. Occasionally, frames overlap; on a roll I just processed, frames 3 and 4, 5 and 6, and 8-10 all overlap one another. Any idea what might be the culprit? I don't know the details on the quick-load system, but it seems that it may be slipping a bit early in a roll? If so, is this something that can be easily fixed by tensioning something?