i have had the same problem. BUT .. in a fit of desperation i discovered that if i removed the screen and VERY CARFULLY slid a stiff putty knife under that bottom piece of wood trim that covers the hadware. (do this from the outside so you dont mess up the inside trim if you slip) the bottom piece is not mitered so it will slide up with a little bit of difficulty PULL ONLY STRAIGHT UP SO IT DOESN'T BREAK. (it's friction fitted nailed, only on the bottom) the wood is fragile so be patient and careful. the finish nails will come out with the milled wood strip
once that is done you can repair, tighten or replace the mechanism.
to replace, fit the wood strip back over the original position (dont tilt it) and line up the nails with their original holes. gently tap into position with a rubber mallet until you are sure the nail points will run back into their original holes. then gently tap it back into place.
you probably already finished but i just ran across this board looking for parts for truth hardware