HP501 paper jam error, adding paper seems to help. Pick up roller not engaged properly.

[WhitmanPrintTec]

Networked HP501dn printer with 3 trays (one manual feed tray and two larger trays). When the paper gets fairly low in Tray 2, and only Tray 2 (approximately 1/4 of tray capacity), the printer reports a paper jam. Adding paper to that tray clears the error and printing continues until the paper gets low again and reports a paper jam. I post this so others may try this proposed solution: The pick up roller in that tray is not properly engaging with a gray bar. This happened after I replaced the rollers as part of a maintenance kit install. By comparing the pick up rollers from Tray 3 and Tray 2, I noticed that there is a small plastic tab that should slot into a groove in a grey bar right by the roller. The tab was not in the groove in Tray 2, but it was properly in the slot/groove in Tray 3. I adjusted the roller and tab to engage with the slot in Tray 2 - and problem solved. The printer successfully processes jobs, even when the tray is getting low on paper.

[Repairatrooper]

Yes, the grey bar forces the roller down onto the paper stack when the tray is inserted. You can see a white lever on the left side of the tray cavity. If you push this level you will see the pickup roller drop down. Glad you were able to solve this and thanks for posting for other users to find.