How 'bout testing the original first.
Simple test for major resistance in switch.
Clip or touch meter leads together - that's zero - whatever it says.
Connect an ohm meter to the feed wire (j1) probably 12 gage red.
Then connect the other meter lead to each of the circuits out and test in the various key positions.
Any resistance that a meter can read is not good.
So if it can't pass that then there's no point in going to a load test.
