I got quite a few of the parts from Core electronics who have lots of stuff and post it out really quickly. The rest I got from ebay which also has lots of stuff, but the post can take 2 or 3 weeks here in Australia especially if the parts come from Hong kong or China.
The electromagnet was removed from a 24 volt automotive relay and is used to pull the cutter down onto the vinyl. Its just a case of removing the cover and pulling the contacts off, so you end up with a coil. This is then wire back to your power supply and the relay attached to the Arduino is used to control it.
The internals of the printer head are removed and after some trimming, cutting and careful positioning the coil can be put in place.To test it you can use the spindle on tick box in grbl and this will turn the relay off and on.
Positioning the coil is quite difficult as it need to be square, flat, and not quite touching the cutting plate when energized. I spend quite a bit of time getting it just right before gluing it down with rapid fix super glue.
Just a note on the rapid fix super glue, if you can get it it is the best glue that I have ever used. It like super glue on steroids and it comes with a powder that can be used to fill large gaps or holes