I bought this cabinet about 20 years ago. I think it's a Model 2196 from around 1976. Inside the cabinet it looks like Jim Marshall's signature in pencil and another signature from somebody who's intials look like JC. Would the presence of the signature increase the value of the cabinet? It's pretty beat up and did not come with the original speakers. The Vintage 30s in the photos are mine. Can anyone offer a ballpark figure of its value or suggest a resource where I might get help determining what to ask for it? Thanks.