Phaser 850 paper jam after 2 prints

[MVL1]

When printing from the lower paper tray on my Phaser 850, it jams after printing two sheets (only one additional tray is installed).
When I open the lower tray, the top sheet has been fed just up to the top of the tray (just above the point where the rollers pick it up).
When I remove the sheet and close the drawer again, The printer returns the message that there is another media jam. This time a sheet has been fed from the standard tray just up to the point where it reaches the paper sensor on the right side of the rollers.
After removing this second piece of paper the printer does its trick with printing two pages and then starts the error cycle again.
Does anyone have a solution for this problem?

Thanks in advance for any suggestions.

 

[phaser860]

clean and check upper transport rollers for worn out.
check D/M clutch..for defective

 

[MVL1]

Phaser860 thank you for responding.
The upper rollers seem OK to me. However, I am not sure what exactly you mean with this D/M clutch, is this the clutch/gearbox on the paper pick arm?