Until now, I have been really happy with ink flow with my Montblanc M Ultra Black. I could pull out the pen and it would keep writing or sketching until I put it away. In the recent month or so, I am not so happy. I will pull the pen out, the ink will flow fine for several minutes, and then no ink will flow from the pen. I will usually have to violently shake the pen to get the ink flowing again. I have been using both Montblanc Mystery Black ink and Montblanc UNICEF ink and have experienced this behavior with both. I have disassembled and soaked the pen for about half an hour in filtered water between changing ink, but the behavior comes back. The pen gets used daily.
Do I need to soak the pen overnight, use pen cleaner, or does the pen need to go to Montblanc for service? Thanks for your responses. Here is a photo of the pen.