Well, since there doesn't seem to be a factory schematic available, I traced the amp myself. The rectifier and power transformer are definitely not stock. I'm not 100% sure that the amp shipped with EL34's either, since the Jensen C12P speakers weren't the highest wattage speakers available from Jensen at that time, and are rather underpowered for a pair of EL34s in class AB. However, the cathode bias resistors are period correct, and the tube sockets look original, so it might have non-original speakers, or just might have been a bad choice in speakers. It's possible that it originally came with 6v6 tubes though. "EL34" was written in marker next to the power tube sockets, suggesting that this wasn't standard. What do other guild amps from this era tend to use?
Regarding the bad channel: It was a blown speaker. I'm having Weber recone them to a 50W rating.\
Regarding the SS rectifier: The original power transformer was replaced with one from a Twin Reverb, so no 5V rectifier heater tap. Hence the switch to diodes.
My schematic is posted here:
Guild 200-S
One gain stage! But that doesn't stop the amp from sounding like Townshends amp from Live at Leeds when dimed!