Speedometer and Odometer - '88 S-10

I was on my way to the Mojave desert this weekend and well about 95 miles in my speedo stops working which in turn stopped the trip/total odo.

I imagine this fix is something like a loose screw or spool so shouldn't be that tough.

Question is:

Is it just a screw? If so how do I get to it?

-Side note-
It is really interesting driving a car through the desert plus the 3 hour drive home without a working speedo and a check engine light glaring at you all the while.