My Dremel tool motor still works but shaft won't turn?

Here's the email from I got from Dremel (in my case the flex coupling broke):
Inside the tool is a flex coupling and spline driver.

The flex coupling is # 2615294309 and the price is $ 1.25.
This is the hollow plastic sleeve about 1" long with grooves on the
inside, that goes between the motor shaft and the output shaft.

The spline driver is # 2615294308 at $ 1.00.
Spline driver sits on the direct end of the motor shaft. The flex
coupling sits over the spline driver. Spline driver is about 1/4",
hard plastic with grooves on the outside.


Total shipping for orders under $ 5.00 is $ 2.50. Orders over $
5.00 is $ 4.00.


I have provided ordering instructions below.

To order by phone: 1-800-437-3635, Monday-Friday from 7 am to 6 pm
central time. VISA, MasterCard or Discover is accepted.

To order by mail:
Dremel
4915 21st Street
Racine WI 53406

The issue is a coupling - pn 2615294309- if you search on that in these posts, you will find other info as well.

From looking at manual there is no transmission or connector so the only possible explanation is that the shaft is broken. You might try calling this number
1-800-437-3635 to see if they repair or can further advise you.