Well, it sounds to me like the EB is working as it should. My take is that it's simply one of the cheap ones that Monaco put on some of their coaches. I know the one on my Dynasty was junk because when I put on the PRXB that thing could stop me a quickly as the service brakes. HUGE difference.
Frisbee, change out was simple. Unbolt the old one and bolt in the new one. Change out the vacuum line and you're done. Great instructions came with the PRXB from PacBrake. One of the best mods I did on the Dynasty.....Dennis