Having trouble with a MB 146, which is not sucking in ink. The piston seems to be working fine in its movement. Initially, had to clean out the ink in the pen by keeping the Nib and part of section submerged in warm water, flushing with whatever little water it could take in. Did this several times. All the above didnt make the ink filing work. So, after getting the tools from eBay, opened the nib unit and the piston (and greased it) and put the parts back. Then, tried to fill in water in the pen through its normal filling system (nib and the piston mechanism), it still doesnt suck in the ink. When it was working, had used only Yama Dori ink. This was not a new pen, but was in a good condition when received and has been used for only 4 ink fills since then over 6-7 months. Seeking advice from fellow members.