The panel did appear in 65 episodes on the 80 (including The Cage).

1 00 The cage

1 01 Where no man has gone before

1 02 The corbomite maneuver

1 03 Mudd's women

104 The enemy within

1 06 The naked Time

1 07 Charlie x

1 08 Balance of terror

1 09 What are little girls made of

1 10 Dagger of the mind

1 11 Miri

1 12 Conscience of the king

1 13 The galileo seven

1 14 Court martial

1 15 The menagerie part I

1 17 Shore leave

1 18 The squire of gothos

1 19 Arena

1 20 The alternative factor

1 21 Tomorrow is yesterday (panel is off)

1 23 A taste of armageddon (panel is off)

1 24 Space seed

episodes 1 25 to 1 29, the panel is off

2 01 Catspaw

2 03 Fridays child

2 04 Who mourns for adonais

2 05 Amok time

2 06 The doomsday machine

2 07 The wolf in the fold

2 08 The changeling

2 09 The apple

2 10 Mirror mirror

2 11 The deadly years

2 13 Trouble with tribbles

2 14 Bread and circuses

2 15 Journey to babel

2 16 A private little war

2 17 The gamesters of triskelion

2 18 Obsession

2 19 The immunity syndrome

2 20 A piece of the action

2 21 By any other name

2 22 Return to tomorrow

2 23 Patterns of force

2 24 The ultimate computer

2 25 The omega glory

2 26 Assignment earth

3 01 Spectre of the gun

3 02 Elaan of troyius

3 04 The enterprise incident

306 Spock's brain

3 07 Is there in truth no beauty

3 08 The empath, panel is off

3 09 The tholian web

3 10 For the world is hollow and I have touched the sky

3 11 Day of the dove

3 13 Wink of an eye

3 14 That which survives

3 15 Let that be your last battlefield, panel off, then visible behind Sulu

3 17 The mark of Gideon, empty bridge, then panel off

3 18 The lights of zetar

3 19 The cloudminders

3 20 The way to eden

3 21 requiem for methuselah

3 22 The savage curtain

2 24 Turnabout intruder

In some other episode scenes, the panel is off

In The City of the Edge of forever, the panel is missing,

probably dismounted for repair.