When my old man was an operator, the shop assistant would write "Out of Order" on a piece of paper and slide it under the glass under Dad arrived to fix the game. Why not sticky tape to the backglass ? Because kids would remove the sign and stick it on another game to "reserve" it for them to play the next day.


If the game had to be returned to the workshop, the old man would write "UTS" on a piece of paper... I have boxes of PCBs with "UTS" written on them in storage.


"UTS" = "Up The Shit".