[quote=“mpainter1, post:3, topic:78100”]
if anyone could offer any suggestions as to the source of moisture/QUOTE]
Do not bother looking behind the wall.
It is from rain events. external. It is trapped within the brick. The interior double wall is void of MC. If it was not the drywall would show signs of apparent elevated HR or even MC above the norm. Mr. organic growth my be present also. Not saying it does not happen. The occurrence is rare.
Weep holes are for atmospheric pressure relief in double wall envelopes.
The exterior is a high pressure forcing MC into the medium pressure void and the interior space being a low pressure zone. hence forth perm barriers.