Just had mine replaced here. $286 and change.

 

Though I've not had to change the ignition cylinder on the HHR or on my GTO, I notice that they have several 'how to' type threads on the GTO site and many have stated that they've done it successfully. How hard would it be to change it yourself on the on the HHR? The part appears to be less than $50 + shipping at GM parts direct.

 

This is the closest thing to a "How To" that I've found here....

https://www.chevyhhr.net/forums/problems-service-repairs-42/ignition-cylinder-lock-20649/

 

Oh, I see. The part that fails in the HHR cylinder is different from the part that fails in the GTO cylinder. On the GTO, you don't have to worry about resetting the lock pins/ wafers to work with the key because you're not changing that part.