External charger hookup

I’ve got a 2002 GEM with a bad onboard Q charger, I purchased a 72V Schumacher Charger but can seem to get it to work on the GEM.
I believe I’ve got the leads to the correct points but not sure, doe anyone have any experience with the use of an offboard charger on a GEM.

Maybe a schematic of where the +/- leads need to be??