The lever inside the printer is in the wrong position as shown below.

Remove the printer cover and the push tractor. Raise the lever as shown below and do not move the lever afterwards.

After installing the push tractor, the release lever is locked.

When installing the push tractor, the release lever is in the wrong position. Remove the push tractor and lower the release lever to the single-sheet position. Then re-install the push tractor.

Using the Printer 3-31