For 1937-47 Charlton's added MS66 and removed EF40,still the same number of columns,simply a matter of not having to create a new table.
The EF40s are not now worth FV,but they never were worth the $5 as published in Charlton's,more like a buck or less.
Never use Charlton's as a price guide,you'll be sorry if you do.Use their prices for relative values only.
"Dipping" is not considered cleaning...
-from PCGS website