No use in keeping a dangerous amp original. They are not rare, they are relatively cheap, and I wouldn't give a plug Nickle for an original 400 UNLESS it was to gut it. But, good luck. I've never had to buy a 400, they were given to me. The one that worked, I gave to my friend who lived in a trailer which needed burning (The trailer that is), and I gutted the other 2 for a proper WOPL job.