I will admit it. Even after 25 years of research, occasionally a microfilm machine will confuse me. Sometimes I hesitate to ask for help. After all, I should know how to use one. And then I remember, waiting only wastes time.
If there is something at a library or archives that confuses you or you do not understand, ask. Staff can usually help you operate the equipment.
If it is a record or document they cannot help you with, it might be because it is unusual and something with which they are unfamiliar. In that case, consider asking the question on a genealogy mailing list or at your local genealogical society meeting. Someone there probably can help you or point you to someone who can.