All 12 in the listing table below are complete, no missing pages, all legible & worthy of preservation IMO.
Came across them online in UK recently & won them for a modest price.

Ebay listing pic above.
81K1 to 81K14 16pages
107w4 107w6 107w7 24pages
107w102 24pages
112w140 24pages
131w101 131w104 131w110 20pages
143w2 143w3 20pages
147-106 & 147-107 22pages (no cover)
151w1 151w2 151w3 24pages
246K3 & 246K5 14pages
246K13 & 246K15 12pages
400w1 & 400w5 32pages
400w21 400w22 400w25 400w26 400w30 & 400w33 38pages
(660g 1.45lb bare weight) Circa 240 pages to scan.
Non Singer
Instructions & Parts Book for US Machines 32pages
Instructions & Parts List for Bellow Blindstitch Machines Small folder/typewritten sheets

My only Singer Industrial. Main interest for me was the rotary take up & distinctive shape from the late 50s Sputnik era: )
Twelve Singer manuals in all, looking to be around 1940s. I can see no dates on any. I’ve only ever had one industrial machine but skimming through these there are some amazing machines contained within: ) Some may be hard to find these days, but if I had one of these machines I would love to have a physical copy of the original manual, even if I’d found a digital copy online.
My intention was to get them uploaded to ISMACS database where they would be free for anyone to access/download. However with 240 or so pages to scan/copy it is too much for me personally & I’m looking for a volunteer, or realistic suggestions as to what to do next. I have a Contacts Page in the menu above.