Garage storage may have some bearing on the demise of the plastic. Less than optimal temperatures and, if cars are stored there, there may well be some pollutant damage.
I used an old A frame stand yesterday (not a Hercules) which I’d been storing in the loft, took it to a gig and, upon opening it, the rubber at the apex just split. The environment in my loft had obviously degraded it (plus, it was probably cheap). Fortunately, not as a huge disaster as having the height control section let go on the OP’s Hercules (I have one of these too, which I may now remove from the loft to a more stable environment).