I Need chip I.D on Autotek Stealth

I'm working on an Autotek SX1500.1.
It's the one with the big slab of chrome on the top.

The digital driver IC 3 is shorted. (Suckes the -15v way low)

Of course the ID on the chip has been ground off and Maxsonics won't offer a schem to a non warranty tech.

They're telling me that parts for these models are no longer available anyway. (I get the impression they don't want to help?)

It's a 20 pin DIP mounted on a socket located just about in the middlee of the board.

I may be out of luck on this one.