Polaris Window
Thanks for posting. See our 26-438 Pivot Bar. This is often seen with Polaris windows. However I have no way of knowing for sure this is the pivot bar your window needs without seeing the original, so I highly advise checking an identical window elsewhere in the house to confirm this is the right choice.
That stamp on the back of the pivot bar, 98-31, has been associated with both the 26-438 and 26-336 Pivot Bars. I am afraid there is really no further way of narrowing down which one it is without seeing it removed. I apologize for the inconvenience.
As far as removing the sash, see the video below that shows how to remove and replace coil balance assemblies like this. It should just be a matter of getting the pivot bars removed from the cams in the pivot shoes. Let me know what steps you are having trouble with.
It's possible that the pivot shoe assembly is already broken, which is why you're having trouble tilt the window inward. Does it work more easily from one side or the other? If the window is otherwise identical to the ones not giving you trouble then this should be the right method--it may just be the hardware in there is busted. Can you lift the sash at all before tilting it inward? If not, or if it immediately slams shut, that would indicate the coil spring systems are broken as well.
Thanks for doing this. This does look like the 26-438 to my eye. Just review the measurements to be certain.
