Now I understand what you meant. I didn't know you could do that to test if a PSU is working. Handy tip for the future!
Alas, the GE one is well and truly dead. And the MDD would involve quite a bit of dismantling and cap replacing to get working. Honestly considering how little the machines are worth it's hard to justify putting any money into repairing or replacing the PSUs so I think I'll just put them on the back shelf for the time being.