Pella shade between glass - pulley cord

Hi,
I have a Pella picture window in the family room which has a shade between glass. The shade operated through a handle that works on a pulley mechanism. Over time, the pulley cord has started slipping through (the jagged structure that holds the cord in the lever is flattening out. For now, I cut a small piece of the cord but it is tight now and I think it will not last long.

I'm looking to buy the replacement cord but can't find the part number. Can you pls help