DC14's and DC15's have two types of wand on them. There is the early type with the removable top collar secured by a half circle clip, and there is a later type with the red top.
On the photo above, the early type is on the left, the late type is on the right.
And they look like this.
DC14 type
DC15 type
Please note, the two types
LOOK the same but they
ARE NOT the same. The DC15 is smaller in diameter and the colours differ.
To replace like with like, you simply remove the half circle clip from your old one, pull it off and fit the new one. Easy.
However,
only if you are practically inclined, you can replace the later type red collar
(that isn't available or even designed to be removable) with the wand collar to suit the early type.
I am going to show you how. You will need a small angle grinder fitted with a cutting disc. Perhaps a Drimmel type product will also do the job. We use a grinder.
So you have a scruffy red top you want to replace that looks like this:
To remove this, use the grinder (or a hacksaw) to carefully cut it off like so: