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McIntosh C-4 preamp schematic

I could use some help. I'm trying to restore my McIntosh C-4 preamps, but the Sam's photofact does not match what is inside my units. I have a solid state rectifier providing DC 6V filament voltage that is not shown inside the chassis. Also, layout of components on the main board is different. My serial numbers are 6983 range. There must have been a change in circuitry along the way? Schematics I have found are from 1955, and my units were built in 1957. Anyone know of a way to get correct schematics? I had the same problem with my MC 30 Power amps. I have two of them, but they are built slightly differently and I had to find two different schematics online to properly service each one.
Any help appreciated.

Re: McIntosh C-4 preamp schematic

I think the information you need is in Sams 423-14. Send a message to me with your email address and I will scan the document for you.

Re: McIntosh C-4 preamp schematic

Thank you!
I figured it must have been a change made from the original. Looks like a solid state DC filament supply was added in addition to other changes in the circuitry.