Troubleshoot your pen: dial vs delivered, leaks, drops and a stuck dial

Usually not a fault. In the order we see them:

1. The pen has not been primed, so the piston rod has not reached the cartridge stopper. On a fresh cartridge the first presses move the rod up to the stopper and push no liquid. Prime the pen: turn the dose knob to 50 or 60 and press the button until the piston rod meets the cartridge stopper. You may need to repeat this a few times. Do NOT force it: stop pressing once the piston sits gently against the stopper.
2. The cartridge holder is loose. If it is not screwed on all the way (or, on the V2 New Style, pressed on and twisted until it locks), the rod cannot push the stopper the full distance. Seat it until it stops.
3. The pen was pulled out too soon. After the window reaches 0, keep holding the button for 10 seconds before removing the pen tip, then release the button.
4. The cartridge is nearly empty. If the window stops above 0, the cartridge ran out partway through. The remaining number is what still needs to come from a new cartridge.
5. Air in the cartridge. Screw on a new pen tip, dial 1 and press until a bead of liquid appears before each use; see the priming guide.

• Needle not fully seated. A pen needle that is cross-threaded or only half screwed on lets liquid past the septum. Remove it and screw on a new one straight.
• Holder not tight. On the V2 pens, seat the cartridge holder fully (screw it down until it stops; on the New Style, twist it until it locks) so the cartridge sits square against the needle hub.
• Cracked cartridge. Glass that has been dropped or frozen can crack at the neck. Take the cartridge out and look at it against the light. A cracked cartridge is done; load a fresh one.
• Needle left on between uses. A needle left attached is an open path. Liquid can weep out and air can get in. Remove the needle after every use.

Normal with any pen needle. Liquid in the needle channel keeps moving for a moment after the mechanism stops. To get the full dose out, press the button all the way to 0, keep holding it for 10 seconds, pull the pen tip out, and only then let go of the button. The Auto Pen's manufacturer says to hold for at least 6 seconds, and that a drop or two afterward does not change the amount delivered.

• V2 pens, piston stuck: The piston is spring-loaded, so a cartridge must be installed. Prime the pen: turn the dose knob to 50 or 60 and press the button until the piston rod meets the cartridge stopper. You may need to repeat this a few times.
• Auto Pen, knob stops: the cartridge has less left than you are dialing. The knob will not turn past the remaining amount. Do not force it; load a fresh cartridge.
• Dial feels gritty or jams partway: liquid has got into the dial mechanism, usually from washing the pen under a tap. See the cleaning guide for what to avoid. A pen that has been submerged may not recover.

On the V2 Original Style, the cartridge holder is part of the pen body and sits under the cap. To access the cartridge holder, the pen must be screwed together, then simply PULL the cap off (do not unscrew).

Email [email protected] with the pen model, when you bought it and what you have tried from this page. Photos help. All sales are final for hygiene reasons, but a pen that arrives damaged or wrong is replaced when you tell us within 48 hours; see the return policy.