Yes, the fine folks at SIRS wanted to ensure their profit margins would never erode, so they made little triangular shaped heads on the adjustment screws. And now we get screwed whenever we lose the adjustment tool! Just make sure you're sitting down when you get a quote for a new one.
If ever there was a case for 3D printed tools, THIS is the one to start with. SIRS adjustment tools are a huge ripoff.
(I keep mine taped to the inside surface of the lid of my big roller toolbox so it won't get lost, and it's got a big loop of lacing cord tied to it and a cardboard flag on the lacing cord. No way I want to pay for another one of these things!).
You might want to try taking a stick of plastic (something like a sprue from an aircraft model kit) and getting it warm with a bbq lighter, then pushing it onto the adjustment screw. This might allow the plastic to mold itself to the triangular shape of the adjustment screw.