WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
Push rod engines
Inspect the roller for flat spots or scoring. If any damage is found, inspect the camshaft lobes and valve tappet for damage.
Fig 1: Inspecting Roller Follower
Courtesy of FORD MOTOR CO.
OHC engines
Fig 2: Inspecting Roller Follower For Flat Spots/Scoring