by DonaldNZ » Sat Feb 16, 2019 5:23 pm
often a bread and butter knife will do it, or a jewelers flat screwdriver, warm it up to 50 - 70 degrees C so the plastic is only just too hot to touch, then it'll be alot harder to split the plastic.
if its sealed unit hold them in the vice with only 1mm proud of the jaws and use a hacksaw 5 mm up from the bottom swage or joining lip, do this to all sides , the 1mm stops you hacking into the winding as much
If you're for real, and plan to reuse and not just for inspection, do it on the side [ one end ] of the vice jaws so the plastic filings don't all fall into the relay and cause grief down the road.
after making your contact a beautiful thing with 1mm of post make travel to promote self cleaning, get your magnifying glass out to inspect for plastic swarf & stick it back together with your handiest sensor safe neutral cure [ no vinegar smell & doesn't eat copper] rtv [room temperature vulcanizing ] silicone sealer adhesive.
Once cleaned, the contacts will be addicted to your treatment every 5 years as you may be through the hard surfacing on the contact faces. worth it if it'll save you a hundy.