Lexmark MS823dn paper jam message when tray 1 is empty

[Lexmark20242025]

Newer MS823dn (only 400,000 mono pages), when tray 1 runs out of paper, it shows "paper jam"....this goes away when filling paper. I read something about a possible problem with the paper feed sensor. I second tray is present, but not able to use it as it gives this error instead of proceeding to the full 2nd tray.