Been wanting to do this for years and finally found a great pictorial on every step of the process. Removed everything from the receiver and disassembled the forend so I could clean up the wood. Used some stripper and a scrub pad to remove what little finish remained on the stock and forend. Sanded lightly and applied 3 light coats of TruOil and buffed it out between coats with fine steel wool. Gave it some protection without shine. Expected some grime inside the receiver and under the bolt, but was surprised at what was inside the magazine tube. This gun was manufactured in 1937 and that area (magazine tube) had never been cleaned! Had some mismatched screws in the magazine tube so I ordered a screw replacement kit. Fit perfectly. Also ordered a forend wrench which made the job of removal a breeze for such an old gun. I'm pretty sure that had never been off the slide. Here's a couple pictures of it in pieces and after assembly this morning. The forend is still assembled in picture #2 as I was waiting for the forend wrench.
Model 12, Assembled 1937, 32" Full Choke 2-3/4" Chamber