[HAM] #8 Drawbar malfunction

[Jim and Carolyn Griggs]

Recently bought a 1956 B3.  All four #8 drawbars do not work.  No notes play when only these drawbars are pulled.  Apparently the organ once had a "Nova Bass" unit on it, but it was removed before I bought the organ.  Almost all the presets had been rewired from the factory settings, particularly the grey wire (#8).  Just changed the presets back to the factory settings.  The four #8 drawbars still do not work.  Bus bars are clean, organ sounds bright, but no #8 drawbar response.  Has anyone had a similar problem.  What single wiring change would disable all four #8 drawbars?  Thanks for any suggestions!