I like the Montblanc Le Grande Rollerball, but, I have mixed feelings about the cartridge.
When they work, they work fine. Finding one that works can be an adventure in itself. I have never had this problem with the smaller Rollerball Cartridges.
I got four at a jewelry store, and when I got home the only one that worked was the one I tried out.at the store.
I called MontBlanc and they sent me replacements.This time. I used one and put the rest in a heavy duty, sealed Ziplok bag, put in a box in the closet.
I just opened the plastic bag to get a new cartridge out of the bag, only one of the three work. I expect a little more for what these cartridges cost!
I decided to get creative. My back-up pen is a Tactile Turn Copper Mover. It uses a Pilot G2, which is nice to write with.
I tried the G2 in the tip of the pen. The tip of the cartridge extended far enough out of the pen to be usable for writing. It needed a back spacer to hold its position in the pen. I tried the spring from the Mover and it worked. I was able to write using the G2 cartridge in the Montblanc.
When, I took it apart, the spring stayed in the main body of the Montblanc. I used my EDC tool, a re-shaped paper clip, to pull it out. The spring can be ordered from Tactile Turn.