I don't know exactly when the switch took place, but I have noticed that "later" Chinooks use a different attachment than my '99. The later ones use a "typical" RV screen door latch (you reach through the gap made by sliding the cover plate sideways, and it's a little dohickey that you release).
However, on my '99, there is a built in magnet system consisting of two different sets of magnets for the two purposes. There are round plates recessed into the main door, and the screen door "attaches" to those with matching round magnets. No latch! The two doors stay together "automatically" in normal use, and you just "pull them apart" when you want to separate the screen door from the main door.
Then there is another magnet (two thin bars in one fitting) on the screen door, with a matching plate on the Chinook door jamb (body/door frame) that holds the screen door to the doorway (to keep it closed when you are only using the screen door and have the main door latched open).
I noticed that on mine, the "another magnet" was over-riding the round magnets, so the screen door would tend to stay magnetized to the Chinook, and not "stick" to the main door (when I just wanted to open them both as a unit). I think the reason is that one of the round magnets is missing from the inside of the screen door, making it only 2/3 as powerful as it should be. I haven't as of yet looked for/found a source for the round magnets, so I guess my "bailing wire solution" is working too well
-- but what I did was put a piece of tape over about half of the "another magnet" (the one that is two long thin bars in a single fitting) on the inside of the screen door which made it less strong. That achieved a perfect balance between the two sets of magnets: Now the screen door "sticks" to the main door all the time - unless/until I pull the screen door off of the main door on purpose. The screen door also sticks just fine to the (now) "half a magnet" that holds it to the Chinook body when you only want the screen door. So all are happy and no latches (they were never installed since the magnets were used instead as per Chinook originally).
So if you have a magnet system, maybe this will help. Just look for the following:
1) On the main door (inside surface) three flush round metal fittings embedded in the door along the side opposite the hinge (in other words, inside the door near the opening side).
2) On the outside of the screen door, three corresponding protruding round magnets
(My lowest one of these is missing, hence my "tape balancing" mod.)
3) On the inside of the screen door (just above handle area), a metal plate with a magnet consisting of two vertical lines of magnet.
4) On the outside of the Chinook door jamb, a metal plate that "catches" the magnet from #3.
The #3/#4 system is where I put a piece of tape to reduce its strength. If/when I find another round protruding magnet to replace the missing one on the screen door, I don't think the tape will be necessary to "balance" the system.
It's pretty slick, really. Let me know if you need photos to visualize. Also if anyone has replaced the protruding round magnets on the outside of the screen door, and has a handy source, I'd like to know it (the round plates that are recessed into the main door are fine; it's just that one of the matching protruding round magnets on the screen door is missing)
