[Swan] Swan 1200Z bias circuit

[K2VY]

Hello fellow Swan fans,

I have searched the entire archive for threads relating to the 1200Z 
amplifier and only found info about the 1200X. Since nothing was found, 
I am posting the following:

Swan model number:  1200Z
Swan serial number:  156
Tubes:  6MJ6 (x4)

Question about the bias circuit:

The schematic shows R19 (5K pot), R22 (3.3K, 2W) and R23 (1K, 2W) as the 
bias circuit. This is what is presently in my amplifier, which agrees 
with the schematic. My manual, which I believe is original, shows the 
same parts in the parts list, but the bottom view of the chassis shows 
R19, R20, CR11 and Q1. However, the parts list also includes CR11 
(1N4005) and Q1 (MJE521), but does not include R20. R20, CR11 and Q1 do 
not show up anywhere on the schematic.

Does anyone know what the "correct" bias circuit is?

Thank you very much for your help and 73.

Dan, K2VY