Hi, I'm considering buying a used Germino Classic 45 head. The person selling it says the serial number is 006. What I'm wondering is, I read in the User reviews that earlier models, though they sounded great had a slight problem with the tone stack, and there was a mod that came after (well...rather than a mod, actually they changed it for all models after) that made the thing fantastic. Question I guess is, anyone have the earlier mode, or both and can tell me how much of a difference it really made, and also anyone know how difficult the mod is ? THanks!