The hardest part on the electronics, is prying them open. It's sort of like a puzzle. Other than that, you're replace 2 wires with 2 wires, and they (in my experience so far, 1/2 dozen done) aren't polarized, even on the electronic ones. Top left and top middle should be at least looked into. The wide Singer one, I had bad luck with, fragile thin copper contact strips that had arced through.