Replaced all 8 rollers as 5 had either cracked or broken, resulting in top rack track coming out of the rollers and dropping.
Removed the end caps on the tracks
Pulled rack out
Removed 8 T25 torx bolts
Replaced bolts with new ones
Seat washers on new bolts
Reinstall bolts and washers
Replace rack
Replace end caps
It was a very easy repair and reasonably low cost.