Sew...is there a different kind of bobbin caddy that fits the 15 series?
 

Why won't my fits-all Singer or Kenmore bobbin caddy fit into the 15-91?

Do you mean a storage unit for class 15 bobbins or the bobbin case that goes in the machine? If it's the bobbin case, you have to check if you have an "eleven o'clock finger case" or a "one o'clock finger case", either of those usually fit if Singer model 15 is on the list of machines in question. Some of the oldest model 15 might have their own peculiarities, but since your's have reverse lever and potted motor they are not relevant. I hope some on the forum will let you know if there are anything else you need to know.

What's a bobbin caddy?

That's the girl who carry all the bits and bobbs for the important dressmaker ;)

Okay, I'm thinking it's the 11 o'clock style, is that an Internet only find?

No, it should be available other places too, but it's easier to get the right part from people who know what you are talking about.

Sew-Classic.com carries the different styles of class 15 bobbin cases and explains how to tell the difference.
Rodney

Most Singer 15's will take the 1 o'clock style, however later 15's (75 and 125) take an 11 o'clock style. Most non-singers take an 11 o'clock style.

My new 15 is a 15-91 from '39 with the 11 o'clock bobbin case.

Singer 15-88 through 91 take an 11 o'clock. All of my Japanese machines except my FZ2 Pacesetter take a 1 o'clock. The FZ2 is a rotary machine.

Cari