Found a Zenith....

[DavGoodlin]

I had one of those and the dial has a round shaft gripper with a tension ring.
If you pull on the tuning wheel from the back, it will pop off.

When you put it back together, make sure you tune it to a station of known frequency, in the middle of the band, then align the dial/pointer before pushing it back together.

Looks in fine condition and I bet the tubes are all OK. One of the last tube radios?

Edit: This radio, like many from the mid-60's had tension rings with a set of ears that prevented knobs from being pulled off completely, exposing a metal shaft that was possibly energized with line voltage.