Trying to get to my Nacogdoches appointments and our brake valve "hung up" at startup. The hissing stops when the service brake is fully applied, but continues to leak air when the pedal is released. I pulled the part tag while muttering bad words: "Midland N4506A 254K"<br/><br/>Here's a photo of the part. Checking Haldex sites, the valve is obsolete. Of course, FOT and NAPA are...