This maybe a simple question. I have been working on parking brake problem and resolved it or perhaps part of it with a bad hose.
My parking brake button kept popping out and not setting the parking break. I found a brake line in the rear was bad and replaced that and now it appears to be working.
During the troubleshooting, I noticed that while the parking break is released I hear a significant amount of air being released from the inversion valve at a brass covered exhaust port. I put pictures below.