Be careful not to drop your edge finder. The spring may become damaged which will stop the tool from functioning correctly.
If you only use your edge finder occasionally, you should oil it about once a year. If you use it frequently, it will need to be oiled more often.
You may need to pull the parts slightly apart to get the oil in between them. If this is the case, make sure you don’t distort the spring holding the pieces together as this can permanently damage the tool.
Edge finders should be stored in a ventilated place with low humidity. Most are supplied with a protective storage case to keep them safe when not in use.