It looks like you have both Type 15 and Type 66 (plastic) bobbins in the attachments photo. My bet is your "238" uses a Type 15 bobbin. I often find a mix of bobbins in vintage machines I buy and speculate that the last words the owner uttered when putting up the machine for the last time were, "Something is wrong with this machine, it doesn't run as well as it used to!"
John Thomas in NC