Music Man Stingray II

I have recently become the proud owner of a Music Man Stingray II guitar. This guitar is really vintage from the 70s. All parts are original. After cleaning it, I wanted to set it up for myself. Everything worked fine so far, except for the saddle riders. None of the hex keys or other tools I usually use fit.

So my question is, do you know which tools were used for the saddle riders at the time?

Best regards
Zawo