Kenco Window Balance Problems
We sell a ton of balances and balance hardware, including the fittings, which can be purchased separately. I recommend you browse our full section here to get an idea of what kind of prices you can expect.
That said, when the fittings start failing, that usually means that the balances aren't far behind. You should consider replacing the whole balance just to be safe.
In either event, I will require photos of the hardware in question in order to make recommendations. We don't have access to the records you mentioned as we weren't involved with the original purchases. Please understand that we are not Kenco, we're SWISCO.com, a third party distributor of repair parts. We had nothing to do with the manufacture and sale of your windows.