I've got new electronic (solid state) foot controllers (and new cord sets) for all of my working mechanical machines. The youngest of which is 39 years old (Kenmore 148.13110). New controller works beautifully on my otherwise original Featherweight, and the cord set that it came with wasn't original anyway. I just ordered another one for my 603 and 600E.
I just can't get the feel of button controllers, and the electronic pedals are only a little more expensive than the resistance ones when buying new. I get mine from Sew-Classic.