SH Couch 100 station Interphone in need of repair

[rfkimba]

Hi Guys,
I was offered the above 100 station Couch autophone. The seller indicates "The heavy crank handle snaps back and the selector just points." and attributes it to a spring issue or the lack thereof. The attached photo shows the 100 position dial face above and the mechanism below  which has a significant amount of rust. Having never owned one can anyone suggest who repairs these or a repair reference so I can  atleast have the opportunity to  return the mechanism to work as it should? 
I heard Steph Kerman is a collector but am unable to find his contact info. Does anyone have it?
Anyone willing to venture a guess as  to what the 100 station autophone is worth in good operating  condition? It seems uncommon.
Thanks  Again,
Bob Farber

[Gilas]

Great intercom.  I have one just like this and had the same problem as far as it would just snap back and not slowly tick back as it was suppose to.  I haven't opened it back up since I fixed it but I will try and find the time to do it again and see how it works.