I've found out how difficult it is to research details of mechanics of the time. I'm trying to focus on the Swiss driver - it could of course be Jo Siffert, or maybe Silvio Moser or Charles Voegele. I know the answer you need is the name of his mechanic, but if I can work out the driver, the rest will follow.
Did the mechanic you seek work for Jo Siffert back when he was a privateer?