Any old time mechanic will tell you to repack the bearings...the new ones will tell you "oh they are sealed don't worry about repacking"
Sealed does not mean impervious...grease breaks down with heat,metal expands and contracts and before you know it..dirt and rust on the spindles followed by major repair bills.
I don't care how "sealed" a bearing is it still needs grease and maintanance..
REPACK AWAY GEORGE.
I'ts a simple operation doesn't take more than an afternoon to do. But do it by hand don't use those fancy grease injection gimmicks...they don't work!
John