Hi, thanks for your question!
Knabe was a well known American brand for many years, though they are now out of business. There are sometimes pianos built with the "Knabe" name today which were built by other companies, usually in Asia. Considering the old age of the piano, it will have a rather low value today compared to that of a new piano of similar quality. The work your piano needs mechanically would be expected for a piano this old. I'm not sure exactly what work it needs or if the piano is playable or not, as that will affect selling price. If it is playable and just needs updated then I would recommend $1,500-$2,500. If it is not playable and needs the work to be in playable condition then I would recommend selling for $800-$1,200. Best wishes!
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