Rewire Conrad Johnson Premier 12 from 2 to 4 ohms

Hello Audiofriends,

I bought a pair of these fine amps. The previous owner had them changed from 4 to 2 ohms. I've heard them this way, but don't like the change, too much distortion and lack of push. There's no dealer around here and the change should be doable, if only I had a rewire scheme. Can any one help me? Thanks and cheers, John