Thank you Tennmogger. Its easy to simply dismiss posts by saying, "Go do a search", like I haven't done that already? At this point, I'll simply pull the offending valve and head to the parts house for a replacement. In my 'searching' process, I have found no useful information on the web or this site. If I have time,
I'll post up what I have found in the hope that the next person may have some newer useful information to use.
So far, my best resource has been a retired friend who was a mechanic for the CDF, and later Orange County (CA) Fire Authority and worked on large trucks with similar air brake systems.