CH91 with SF, swapping nibs with a CH92 with M.
Figured it out - a counterclockwise twist on the nib+feed with a firm grip did the trick. Now I've got a flexy nib on the clear 92! The feed on the 92 seems to perform better as well, so this ended up being a win-win.
Edited by aquoro, 17 November 2015 - 20:12.