Since you can duplicate and resolve the symptom by putting pressure on the speaker terminal I would have to say there is a good starting point. I would start by tightening all connections and re-soldering (if soldered)any connection to the speaker terminal.
Those speakers have got to be on the order of 20 years old (I have the mission/cyrus 782's although not currently in use). My speaker terminals on the 782's have a nut that holds a soldered wire to a round lug.
Those speakers have got to be on the order of 20 years old (I have the mission/cyrus 782's although not currently in use). My speaker terminals on the 782's have a nut that holds a soldered wire to a round lug.