Sometime in the 2000s I saw them in Oakland, CA. Jerry was moving slowly and had to be helped out to the stage by a roadie. He was then strapped to a frame that was made up to look like part of the stage set. He stayed strapped to it for the entire set, playing bass and keyboard. The reason for this was that he had sustained an injury at a previous show when he slipped on a piece of a radiation suit that was on the stage. I see they didn't learn from the incident.
Between that and the limited visibility Mark must have in the Booji Boy mask the trip hazards on stage do worry me at their age 😬 That being said they all look pretty spry for a bunch of septuagenarians!