The worst was when it lost traction, shredded the holes, usually in a tangle of paper. There'd also be cases where it kept pulling on the holes but those separ

The worst was when it lost traction, shredded the holes, usually in a tangle of paper. There'd also be cases where it kept pulling on the holes but those separated and got gummed up really badly. When you try and tug the pages out they're all perforated so you get, at best, a single page. It can be a lot of work to clear a jam. Most people think of dot matrix printers as slow, lumbering things that would take measurable time to print a single line. The industrial ones, enterprise grade, made by companies like IBM were dizzyingly fast, pages per minute, so if a jam happened it was usually severe. Most had multiple print heads to speed up printing. These also used much wider paper than normal for things like accounting reports. When they jammed, they jammed.