After a few minutes of web searching, the real story is weirder.
The original Gallagher, Leo, never retired. He did indeed have a heart attack but he's still fine and performing, showstopper fruit smash and all.
His brother, Ron, had been performing as Gallagher II. Gallagher Primary tolerated this for a few years, but then Ron started referring to himself as "the real Gallagher" and giving out autographs as his brother, telling people he was his brother, and worst of all doing the signature watermelon crush. This forced a brother against brother lawsuit in which Leo got an injunction to keep Ron from doing his act.
I can't find the fate of Ron after that. Maybe he had to get a job at Jiffy Lube or something.