Monitor Transister help with Midway Space Invaders.Snohomi..

I have a Space invaders and one of the round metal transisters that
mounts to the metal chassis frame shorts to ground when I check it with
a volt meter so I have determined its bad.I checked the mica insulator
and its good.Sooo The numbers on the transister are (I dont know what
they mean) in the center of the round part are, M for I guess
Motorola.then 7696 under that is 7817 then in each corner by the screw
hole is the number 366a and 817.So my question is is there any
substitutes for this.I have a slightly older monitor with a slightly
different numbers.Or does it have to be this exact one and if so does
anyone have one for sale or a known working chassis or complete monitor
and if so how much are you asking for it.Any help
appreciated....Thanks.....Dave...Oh and what do all those numbers mean.