Jowo nibs are threaded into the the grip section of your pen. Occasionally they get stuck due to ink drying up in the threads, humidity expanding the section or any number of reasons. When this happens and you try to remove it by force it can crack.
The first thing to try is if your nib will not unscrew, pop it in the fridge for a little bit to cool the material and see if that frees it up. If not and you did crack your housing, never fear as you can still save the pen and nib/feed.
Next up is don’t try to unscrew a cracked housing using the nib and feed. You WILL break your feed. This is not meant to have rotational stress and the spine in the feed is very narrow. Just don’t do it. A cracked housing will try to expand as you unscrew it and as it expands it makes the extraction problem worse.
Instead, pull the nib and feed out of the housing and find a flat blade screwdriver that is slightly larger than the opening in the housing. Since it’s cracked anyway we’re just worried about salvaging the pen so don’t worry if you scrape up the inside of the housing. Just don’t force the issue and end up cracking the grip.
Watch the video below for what works for me.