Supro Lap Steel serial # addtl letters

[alibop]

Hello, I recently acquired a Supro Lap Steel. C5414 with the letters FS impressed into the top of headstock following the SN. From what I can tell it is a 1938-1940 Avalon model. 
Black satin body, Supro aluminum plates under the volume & tone controls, no Supro badge on the headstock, strings through the pu, hard wired and aluminum fretboard with parallelogram markers. Orig green lining in the chipboard case. Really strong pu. 
Any insight as the to FS on the headstock? Factory Second? 
Thanks for any thoughts

[Misterkevster]

....perhaps obvious....but pictures always help!!!

[Mark Makin]

Hi Alibop
Firstly you're correct about the instrument - an AVALON from around 1938. The Supro headstock badge was often not used on these instruments because of the two branded knobs on the control plate.
You got me interested in checking all the serial number lists for instances of "FS" marks. In all we only have 10 instruments known across the entire range of Nationals:
These are: 2626FS Sq Nk Style 4 Triplate
3295WFS 12 fret walnut Triolian
1067FS 14 fret Triolian
3787FS 14 fret Triolian
C8847FS 14 fret Duolian
C9500FS 14 fret Duolian
2058FS Rosita
6586FS Rosita

Your instrument, of course, is listed in the late 30s Chicago A,B and C series. In this series we also have
B1979FS Silvo Mandolin
C4123FS Aragon.

I'm sure you're right about "FS" meaning Factory second although, after around 80 years, it will be difficult to assess why it would be a second. Certainly, any scratches or flaws in a perfect factory finish will long ago have disappeared under the wear and tear of 8 decades.

There is another interesting addition to this discussion. There is at least one 12 fret Duolian that has its number stamped as C420-2 which may also indicate a "2nd". There is also a run of 14 fret Style 0s listed as
S5562 2D
S5785 2D
S5958 2D
S6025 2D
I'm also guessing that this also means "2nd"
That's about as definitive as I can give you!!

[snakehips]

Hi there !

I would think the a factory second is the most obvious and likely meaning for FS in a serial number.

However, what would you think of the possibility that -2 after a serial number could mean a 2nd guitar with the same serial number - only noticed just after serial numbers were stamped. Trying to stamp over a number already there would just look a mess. Adding "-2" to the serial number would sort that, then they could miss out the very next number, eg :

C8846
C8847
C8847 - whoops ! C8847-2
C8849
C8850

So this way, C8847-2 could actually be C8848, with no C8848 guitar existing ??

What do you think ?

Are there any instances where you have the very next serial number instrument known, after a -2 or FS ???

Probably a daft idea !