Stevens 335 - need some receiver work

Hello Folks,
My father-in-law thought my wife needed a shotgun of her own, so he found a Stevens 335 12ga with a factor nickle receiver. He sent it to me to refurbish and test. All matching numbers, original forend, needs a buttstock. I'm working on finding a stock (not easy), and have had the barrels reblued by a fellow who specialized in sxs barrels.

When test firing, the left barrel will fire when closing the action, and if it doesn't, it will go off when the right barrel fires. So, obviously this is not a good thing. The hammer to sear interface is poor, or some other problem.

I'm looking for recommendations for someone who loves working on boxlocks, has spent a lot of time working on Stevens boxlocks, who I could send the receiver to for testing, and ultimately repair.

I've worked on some, but I don't want to fiddle with this one right now, and wish to have someone else make sure it gets right.

"Troubleshooting" advice and/or recommendations of folks to contact would be a blessing.

http://i1286.photobucket.com/albums/...psed8feb95.jpg