I just printed out my private key using the console and dumpprivkey and it is completely different to the one I had before.
This is Quarks if that makes a difference.
I don't know anything about Quarks. Unlikely, but perhaps Quarks uses a completely different form of proof of authorization to spend? More likely you either made a mistake before, or you made a mistake now.
I just tried 3 times and still got the same private key so maybe I made a mistake the first time round a few months ago. Wouldn't be my first operator error