Looks as if it was set up for radio with the start/stop buttons on the second group of faders to the right of the four mic channels.
This likely means it has seen pretty hard use.
But it doesn't mean it's not worth restoring.
First, re-cap the power supply and make certain the voltages are correct before firing it up.
Hope you can find a manual for it with schematics.
It will make the job a lot easier.
Hopefully you can find the missing switch and fader caps as well.