I have been repairing a few pens for a friend and a very strange thing happened. I had put a new sac in a beautiful tint GF Wahl and tried to screw the cap on. The cap would not go on and I thought the inner cap had slipped down. I tried to push back up - first fatal error. I then looked for the blind cap for the Parker Geometric in the small tray - no blind cap. The blind cap was now firmly stuck inside the Wahl cap. In my panic to get it out I have ruined the blind cap and also the cap lip on the Wahl. I need to at least find a new blind cap and decide if anything can be done with the now fluted edge of the Wahl cap. I'm usually very careful with my repairs and do little damage. I can't believe when I do it always happens to other people's pens.