Phil:  As for the bell I can live with it…it just sounds a little more subdued than my other SCM units which all have a much larger bell.  I definitely do not see any centering lever on my Classic…it may have been removed for some odd reason as you speculated.  However I have another theory.  This Classic came with a grey Samsonite case that looks on the outside like all other cases like the one that came from 6 series models i.e., Galaxie 12 and Classic 12.  This case is smaller but it has the unique feature of automatically centering the Classic as long as you do an approximate centering before closing the lid…since I have an elite typeface when the lid closes it automatically resets the carriage to “50”, dead center…it also disengages the carriage release levers and frees up the escapement.  This is all done with metal brackets on both sides inside the case. . SCM may have eliminated the centering lever because of this feature.  See the picture.  The manual I have never addressed this innovation.

https://imgur.com/b2Swov9
 

Interesting, that's 100% a 5 series Silent-Super. Pretty cool and very dirty! 
Phil Forrest

Discovered this late in my research...its from the SCM data base.  It's a 1964 Classic that is identical in every way to mine and I don't think it shows a carriage centering lever either.  The serial #'s are very close to  mine being 5X146978 and the one displayed is 5X146261.
https://typewriterdatabase.com/1964-smith-corona-classic.10577.typewriter#description