@daniel_bohrer I recently got a Köhler 11-30 (about the same age) and it runs so smoothly! I will have to replace the leather belt sooner or later, but everything else :blobcat_chefskiss:
I even got the original manual and uploaded it to archive.org
https://archive.org/details/kohler_11-30_naehmaschine_bedienungsanleitung/
@daniel_bohrer and they look extremely similar...