Yeah that is how they go sometimes. After 25 years in that hole it probably didn't really want to come out, plus the old plastic gets brittle.
You should be able to drive it out from the outside. Hopefully you won't have to take the wheel bearing and hub off of the spindle, but that may be necessary too. If that is the case then you may want to take the opportunity to inspect the wheel bearings and races, and clean and re-grease them while apart if they look good. New wheel seal probably a good idea too. It may turn into a little bit of a bigger job than you originally set out for. But maybe not, if you have a little luck.
One other method I have had work out with a stuck wheel sensor, if there is still a good amount of the plastic body left, is to drill a hole in it (from the back side where access is easy), then thread a large wood or sheetmetal screw into the hole. Then you can grab the other end of the screw with pliers and yank it out. Sometimes when doing this, they even start to spin and then come out just by the action of the drill. But if you are already seeing the magnet and no more plastic is left this might not be an option in your situation.
Good luck and let us know how it goes.
