As Tom C said the knobs just pull off. On some sets the horz hold
is an exception. The knobs are common & used up till abt 1970
with different sizes etc.
You will enjoy restoring this much more than the Philco. They were
not famous for there ease of service ! Zeniths are easy & as well built
as any & better than most if not all.
73 Zeno
LFOD !