[HP DesignJet T3500 series]

1. Open the window and check for any visible obstacles restricting the movement of the carriage assembly. If there is a wrinkled mass of paper inside the paper path, lift the pinchwheels and clear the obstruction.
2. Turn off the printer and unplug the power cord. Try to move the carriage manually. Check that the cutter disengages correctly and that the carriage is not blocked by the service station.
3. Perform the scan-axis diagnostic to obtain further information on the problem.

If system error persists:

4. Check the integrity and tension of the carriage belt. If the belt is damaged, replace it.
5. Lubricate the scan axis.
6. Perform a Encoder Strip verification and check it runs successfully.