single arm falls out of position on casement sash

A quick learner from 12518 says:
Hi i have a home full of 20yr-old Norco series D crank-casement windows. All have "Truth" single-arm mechanisms. The little "button/wheel' at the extent of the arms on very many of these windows - the button that inserts into guide the rail - falls out of position. Maddening. I am constantly having to remove screens to facilitate replacing the wheel and then cranking the window shut. I am looking to you folks to an answer: perhaps a simple fix, perhaps an improved design mechanism that i can install
User submitted photos of a window operator.
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Tom from SWISCO responded:
So the wheel bearing on the operator arm falls out of the track, eh? I have a couple of recommendations:

First, check the track where it goes to make sure it's not damaged.

Then, check the hinges to make sure they're not damaged or anything. It sounds like the sash is closing kinda skewed, which could be the result of bum hinges. If the top hinge is hanging up slightly and the bottom hinge isn't, it could account for the operator arm popping out of the track. It could also just be that the operator is broken. With the operator detached, open and close the window manually. Does it seem to work okay? Is anything hanging up? If not, maybe consider a new 39-027E and 39-028E. These look like they might match
A quick learner from New York says:
When I crank the window open and shut, the sash itself is solid and true. Forms a perfect weather seal with the opening. nothing askew about the windows. and the hinges they operate on are solid and installed properly. It's very simply these little wheels that fall out as soon as they find themselves travelling over the middle notch on the track.
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Dave Sr. from SWISCO responded:
I believe you have either the 39-505 or the 39-533 track on your window. In the center of the track, there is a cut out so you can release the bearing from the window track. Not sure, but check to see if your bearing diameter is worn down. It should be 9/16". Also check to see if maybe your track is installed too high on the sash. See if you can reinstall the track just a little lower on the sash. Another quick fix could be to bend up the end your operator arm just a little to keep the bearing in the track.
A quick learner from Toronto, ON, Canada says:
This happened to me - turns out the arm screws attaching it to the frame was loose. Tightened with my handy-dandy multi-screwdriver, all good. Well, the rubber seal is also broken on one side, but that's a separate issue ...
A quick learner from Grand Rapids, MI says:
What I've found is that the window was installed wrong. For my window on the right, looking out, the crank mechanism was installed too far left, 1/2 inch too far away from the wall. When the window is closed all of the way, the wheel runs out of track and slips out. The next time I crank the window open, the wheel is just pushing the track/window out, but is not actually in the track anymore to pull it back in.

I verified that my window on the left, looking outside, the crank was installed 1/2 inch closer to the wall, in the proper spot. That window does not have this problem.

My possible solutions:
1. Unscrew the track, drill new holes, and screw the track back in further to the left.
2. Move the crank mechanism farther to the right, closer to the wall. This will mean making the hole for the mechanism bigger, and will have to fill in the exposed hole to the left with a pvc vinyl filler.
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