It is not listed on the available spares lists online.
Eric the Viking made a brake and there was a thread on here about it within the last year (approx!) not sure which model but the principles he used should apply.
I haven't completed it yet, partly because of lack of time and partly because I'm finding that a slow spin-down is less of an issue in practice than I feared. The blade remains guarded
anyway, and by the time I'm ready to set up the next cut, it's usually stopped.
In short, yes, the principle works (shorting out the motor windings). I've proven this, experimentally, but the approach can't be done with a relay alone because of the arcing on the contacts (the relay life would be measured in days!). You can't do the obvious and suppress the contacts with a capacitor, as it's precisely the sharp change in current that provides the "exciter" effect to turn the motor into an eddy-current brake (there's probably a proper term for this, but I don't know what it is!). The more you take the edge off the switching transition, the less effective the back EMF.
So I'm reduced to a relay + semiconductor solution (triacs), but that adds bulk and complexity, and there is a limited space in the electrical junction box of the saw. It's become a bit non-trivial. The blade arbour, incidentally, will cope with the braking force though, and I've blown 25W light bulbs with the back-emf.
One thought: is your saw 110V or 240V?
Mine is 110V, which complicates matters somewhat.
I'm not sure if 110V ones ever officially had a blade brake. The 240V ones did, although the part is very expensive. That said, there's an Axminster saw that's incredibly similar, and you just might get the braking circuit from them - they're very helpful people.