904 Dipstick tip broke off in trans. Anyone know what would cause this?

Just in case you're not familiar with these old gals, check transmission fluid with the car at operating temperature and running in neutral.
Thanks for the replies. Going to drain it and pull the pan, If I leave it, it will drive me nuts. It's been a while since I wrenched on one of these old babies but did it a lot many moons ago. Car was at temp, in neutral,but found it odd nothing showing on the dipstick.