Sir surreyman . . . . .
BOY ! . . . . . .that little thing is as neat as they come.
If I am guessing correctly on some of the the partially hidden wiring runs.
If you tried one less cell out of circuit . . . likely it is as the illustration below now shows.
With you pulling the connection at C and pulling it back to E area and then disconnecting the connection currently at E and place on the former C connector . . . as the bottom illustration shows.
PLUS . . .my . . . . interconnect wiring links was positively confirmed with your last new photo.
As far as torque, and the wire gauge seen being used , this thing must really be geared down from drive motor to wheel drive.
My recommendation agrees with another's, 1000%, and that would be the mechanical implementation of the physical limitation of the downward travel limit of the accelerator pedal.
PHOTO MARK-UP . . . . .
73's de Edd
.....