The cuffs - the arrow points to one of them - on the hinges should not have cracks or damage. Dirt and moisture are dangerous for the hinge.
The drive shaft joints are protected from moisture and dirt by rubber seals. You should regularly check carefully whether the seals have lost their tightness due to cracks.
Execution order
1. Jack up each drive wheel.
2. Slowly rotate the shaft and check the seal for brittle areas and holes. Traces of grease may also indicate this.
3. Are the clamps secure?
4. Replace defective dust seals as soon as possible, otherwise penetrating moisture will quickly destroy the hinges, and they are not cheap!
[The original material is located on the website «AUDIMANUAL»]