How do you 3d print from an existing part when you have no CAD drawings?
You can't print without a 3D model first. There are various ways you can go about this (or pay someone to do the same for you, ignoring any IP issues).

It is possible to generate a 3D model from a sequence of 2D photographs (there is even software which will allow you to do this freehand on a phone). Equipment exists which is specifically designed for this process, and you have likely heard of the services which allow you to get a 3D print of your own body.

You can take a 2D photo and import this into a 3D drawing package. Copy the features into a mesh, and extrude it. This might be a good approach for a complex shape, particularly if appearance is more important than precision.

For the shape you show here, the simplest approach for anyone with modeling experience is maybe to just draw it from scratch (with a few key dimensions). Your shape is only made up of a handful of primitive shapes.

Experiment in TinkerCad which is an online 3D editor to see if you can handle this yourself. It's not clear if you have your own printer, but this sort of part should cost less than $1 to print.

Strength might be a problem if they are already breaking...