[time-nuts] Austron oscillator coarse adjust?

[John Ackermann N8UR]

While messing with the 1210D-03 I found that the frequency is a bit low
(about -1Hz) and is beyond the range of the fine adjust on the front panel.

There's a coarse adjust hole on the rear panel, but using various tuning
tools including a long, thin screwdriver I can't seem to engage the
adjustment.  If it's a slot for a blade, I can't find it.  It doesn't
feel like a hex adjustment, though I can feel a sleeve that could
possibly be something like that.

I'm guessing that the oscillator in this unit is similar to other
Austron standards, so I wonder if anyone has experience with this and
can tell me what kind of tool works to do the coarse adjust.

Thanks,

John