I snapped mine a few years back and made a quick fix.  Since buying a new reel I thought time to model a new key in case it snaps again.

(Second picture is a product photo to show what this is for those trying to work out if they need this or not.)

Print @ 0.20 with no supports in PETG.

I used the following settings @ 30% infil:

Enjoy :)

All my models are free to download and remix as you see fit, however if you would like to support me please take a look at my Printables Club where all my Fusion360 design files are available to Club members.