help with wiring circuit for MPG using Campbell board

I need some instruction on how to wire a circuit given to me by Jim
Collins (who is at the CNC Workshop) to run my Nemicon MPG with the
Cambell breakout board. The circuit has an NTE123AP am with 3 wires
E,B and C. I think E is ground. His circuit has A of the encoder
coming to the the middle of the amp then a line with an arrow
representing a second wire of the amp to ground and the 3rd wire goes
on to the encoder on the breakout board. Can anyone tell me which
wire is which. The 3 wires on the amp are labelled E, B, and C from
left to right, I think, while looking at the flat side of the amp.

Also, I am looking for a female 6 pin connector to allow a connection
to the encoder receptacle on the breakout board.

Thanks for any help.

Keith Clark