Hi Lance and welcome to the forum!
I’ll touch on a couple of simple things you can try right away. If this doesn’t do the trick then there’s a link below to a helpful PDF file for the Accutron 218 Service Manual that I highly recommend reading (and it’s FREE at archive.org).
First thing is to make sure the battery is inserted with the negative side facing up. Then try tapping the side of the case with your finger. This will often get a stubborn tuning fork etc. started. If it keeps going you’re in business. If not then there could be a number of reasons for stopping, either electrical or mechanical. You can test the cell coil with an Ohm meter. The cell coil is the one nearest the battery. If you get a reading when set to measure resistance then the coil is ok, if not then it’s bad.
Hopefully this helps out but if not then I suggest reading that pdf as it will help explain things much better than I can do up here on the forum.
Here’s the link:
Please let us know how things work out Lance,