Because there were numerous Autocall non-coded systems available in the 70’s, it’s hard to guess what model the panel may have been. If you’re interested in Autocall, http://www.autocall.info/ this page has a ton of information along with company history.
The pull stations you described sound like these:
As far as the horns cutting in and out, that sounds like a malfunctioning panel.
I’ve never heard the term “re-energize” used, but on some very old single or two zone panels, there was a switch that would shut the entire system down instead of a reset or silence switch. Someone may have used that switch to silence the system, then turned it back on before the pull station was reset. But again, without having more information, it’s difficult to guess.