Ahhhh, leave it in there. Ignorance is Bliss.
I can't tell you how many things worked worse after I broke it open after many years of neglect for some good, quality 'routine maintenance'.
There is some magical point in a mechanical beings life that once past, you just leave it alone.
It was mentioned before, but I couldn't tell you how many rear ends are out there on older cars (long before good syn fluids) that ran their entire lives without ever being cracked open. I've seen this in personal cars, and many, many more cases back in my "junkyard crawling" days, looking at driveline parts and odometer readings. *Remember when you didn't need a battery and a key to check a vehicle's odometer? Hahaha.
Anywoo good luck. And I got $20 on you that no one can hang on!