thanks for all the replies.
We are sure that the panel is not in use, and I do not think there is any planned use for the equipment. The overiding issue is - " is the green liquid hazardous in some way, relative to personal exposure or disposal."
Since no one at the location knows what it is, they prefer to figure it out (if possible) instead of assuming it to be "safe".
That leaves me, a non-telphone tech person and about the same age as the equipment, to see what I can come up with. It is obvious that many of you are extremely familiar with the components and I appreciate the feedback.
