Is this a balance? Window won't stay open

Question

Window (double-pane, vinyl, big and heavy) won't stay open, wants to slide down into closed position under its own weight. Attached photos show what I think is the problem. Little round gizmo should fit into the round space in the stirrup-shaped dealie that is still attached to the window frame, but because the stirrup-shaped dealie is dry-rotted and crumbly, any pressure causes round gizmo to fall out. I see no discernable markings on any part of the window or gizmo.... Not sure what to even ask....Is this a coil balance? What do you need to know in order to help me figure out what I need to order? Thanks!

User submitted image of their window hardware.

Tom · Accepted Answer

This part is known as a pivot shoe which is one component to a complete coil balance system. I recommend our 15-180, this looks like a good match for what you have. See what you think! As long as the rest of your balance system is okay, you should be able to reuse them.