89SP air brake wont release, all pressure gauges normal(115) front +rear

[Gregory OConnor]

you dont need the service brake (foot pedal) on to release the
spring brake. I park on a slight incline with the tow hooked and
release the spring/parking brake, let it roll to about 2 mph then
pull the park/spring brake lever to a stop, never touching the
pedal. the parking brake is refered to as the spring brake because
there is a spring that is always trying to apply the brake. when you
release the brake the valve fills a chamber behind the spring and
compresses it in. the drive axle has a brake chamber with twin
pumkin looking things. one pumkin is for the service brake and one
holds the spring. There is a long bolt on each twin pumkin that is
a tool to manualy release the brake for towing or emergancies.

I wonder if the brake camed over??? that is if the shoes are so
worn the lever that pushes the shoe to the drum went past center?????

it could also be modulator valve hung up or the 2 way valve. . I
would try dumping the air by shutting the bus of and pumping the
service brake untill it exhaust then try once again but wait untill
the tanks are full to max before you try and release the parking
spring brake.

if its a valve problem, chock the tires and dont leave air in the
tanks while parked.
Greg94ptCa