Pivot bar

Thanks for reaching out! Your pivot bar looks like it could be the 26-040 3" Pivot Bar. The part you are referring to as the case is the housing. The housing compatible with your pivot bar appears to be the 26-330 Pivot Bar Housing which is used for bottom sashes. 

Take a look over the dimensions for both pieces of hardware and carefully compare them to yours to confirm that these are the correct replacement.

Dimensions for 26-040

26-330 Pivot bar housing Measurements

Profile view of 26-330 Pivot bar housing