Its a mid 70's GT-Matic 100% solid state. Probably the 3
module chassis. They were the first sets to use a master osc for
the horz & vert. That went on to be industry standard. A basic
set to work on so easy.
Other thing is it uses the "Dark Light" CRT & it looks OEM. If it has
a strong CRT it can give a fantastic pix BUT the CRT's were a weak
point. When anything black was on the screen you saw BLACK. Not
greys but BLACK ! Super high contrast if you like it that way.
BTW the key was a sales gimmick. You can open the door with a screwdriver.
73 Zeno
LFOD !