I have a 2001 John Deere 990 tractor That I bought new with 411 hours on it.
recently having a noise while in four wheel drive.
Took the driveshaft out, which is a easy job.
Some ball bearings fell out when removing shaft and cover.
Upon looking at drive shaft, one end was good, with almost no grease,
The other end was missing parts, balls, bearings,ect,
looking at the drive shaft it self, No lubrication, grease,ect.
The grooves where the balls ride was severely wore and balls had fell out, this is the end on the rear end, 6 balls,1 missing. Splines on both ends at tractor are good, no ware.
I will need a new drive shaft, about $400 and some balls, new spacers, 1 plastic piece called seal(?) ect
Cost about $500.
This is a place to regrease every year or two, or even couple of hundred hours.
No mention of maintained in the service schedule?
Do yourself a favor and grease this some at least!!!
ALSO: I have a stump cutter from woodlandmills.ca ,that I used to cut stumps,
75-100 so far
Hope this helps