This may be due to an airlock in the junction between the reservoir and the column, to restore the column flow of a qEV2 or qEV10 column follow the steps below:
1. Place the bottom cap on the column.
2. Remove the loading reservoir.
3. Unscrew the column connector cap and add buffer to the top of the frit until the
buffer is level with the top edge of the column.
4. Screw the column connector cap back on forcing buffer up through the
5. Add 2 mL of buffer to the loading reservoir and allow buffer to run
through until it stops at the frit.
6. Carefully attach the loading reservoir to the connector being
careful to avoid trapping any air bubbles in the connector.
7. Add more buffer to the loading reservoir before removing the
8. The column should begin to flow again.
If you are unsure on the process, here is a video demonstration of steps 2-6.