got one of the good ones,
More like one of the later ones.
The very-first production run used two 2SC2290 transistors for the final amplifier. Trouble is, they were soldered to the circuit board before bolting them to the heat sink.
There was a clearance or spacer-height problem that caused the transistors to be suspended above a 1/8-inch gap between the 'foot' of the transistors and the heat sink surface. Tightening the transistors' mount screws to the indicated torque would not draw them all the way down to the heat-sink surface. They would remain suspended just above it.
Somewhere I have a pic that shows the undisturbed blob of white heat-conducting paste where the transistor was just removed.
Naturally, all the radios built this way went "POOF!" before the mike was keyed the first few times.
Naturally this caused a hit to their warranty-coverage expenses and got corrected the next production run. Later radios had no such "infancy poof" problem.
But the, ah, "five minute" version of that radio model is not an urban legend. But it applied only to that one batch of them.
Unless, of course, you reach inside and crank up the gate bias on the driver transistor. Bad juju.
73