The best protection (before a meltdown occurs) is the Bourns MF-R050 PTC re-settable fuse combined with replacing the factory control switch that is notorious for sticking in the On position. I'll edit this reply with a link to another thread showing how to install them which also includes more info about this melting issue with Fastrack Uncoupler electromagnets.
EDIT: Here are links to a couple of other threads relevant to the uncoupler coil melting and how to wire in protection:
https://ogrforum.ogaugerr.com/...4#158674373762400784
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