For example, asking for a nozzle check can result in a paper jam. The problem seems to be in the number of letter size sheets being fed from cassette 1. The first sheet cues up under the print head and followed by a second sheet feeding into the duplexer. At the next request to print, the sheet in the duplexer jams up with a sheet coming out of the cassette. I don't think this happens with paper from cassette 2.
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