Darrell,
Not sure which parking brake valve you have, but I had problems with mine - Matco - and your thoughts are what solved my issues. The lever on mine was attached over a square cut end of the valve actuator rod. It could be fitted in one of four positions. I finally decided to disassemble the valve and see at what position the cam fully pushed the locking rods - not sure of the terminology, but fine after determining the correct orientation of the lever.