Have an 805 that I sent back to Chartpak two years ago to exchange the nib to EF, have used it daily, Waterman's FB, perfect function. Never dry on startup, perfect flow, no problems. Perfect pen! Decided I wanted a change in ink. For the first time ever, for a complete cleaning before switching to Noodler's Aircorp B/B, I removed the nib, cleaned thoroughly the pen, replaced nib and filled with Noodlers. A little dry on startup and some incomplete lines at speed, but really pretty good and I love the color. Less than perfect function persisted and made me wonder if it was the new ink, so I flushed pen and replaced with WFB and still a bit dry at start-up which had never ever happened before. I know you are to hold the nib carefully away from the tip when inserting and to screw it finger tight and then add a bit and this is what I tried to do. Could it be that the flow has been altered due to too much or too little tension on replacing the nib, or is it something else??

When you say you removed the nib, at first I thought you removed the nib from the feed but as I read further, it sounds like you removed the nib assembly by unscrewing it from the pen. As far as my experience, screwing it in too thightly won't affect the ink flow. What may have happened is that you inadvertently bumped or pushed the tip and bent the tines down a little. That seems a more likely explaination for the interrupted ink flow.

Yes, I just unscrewed and replaced the unit. I never touched anywhere near the tip. I was very careful about this.