Rodney, my husband is sure someone deliberately sabotaged his Mom's machine. He said things were out of adjustment that would not get that way except someone loosed up screws and moved it, and tightened them back up. And it was not just one thing messed up either. His mom had not used it for quite some, and took it in for a cleaning and servicing, and it never worked right after that.
most of my really old manuals have warnings not to take your machine to a competitor for service -as they may deliberately bend something or adjust it wrong so it won't work - in effort to sell you theirs. Several also warn "do not let a tramp repairman work on your sewing machine"