The brief
The Jetta had picked up a clear knock over speed humps that the owner could feel through the floor, and the front tyres had started to feather along the inside edges. Both signs that the absorber linkages had failed and the front geometry was no longer being held where it should be.
The absorber linkages, the small links between the anti-roll bar and the suspension, are part of how the front stays settled and tracks straight. They've got ball ends inside little rubber boots, and when those boots split and the joints go loose, the link rattles instead of doing its job, which is the knock over bumps, and the looseness lets the front wander off its settings, which is the uneven tyre wear. Linkages doing that have run their course.
The diagnosis
A pry-test on the front confirmed it: both absorber linkages had loose ball ends, with the rubber boot split on one side and grease tracking down. One was no better than the other.
With both gone you do them as a pair. Fitting one fresh link against a worn one leaves a stiffness mismatch front to front, and you'd be back for the second soon anyway, so it was both, with a four-wheel alignment after to reset the geometry on the new parts.
The work
Both front absorber linkages came off, and a matched pair of VAG-spec replacements went on, the ball-stud nuts torqued to the manual figures. Then the car went onto the alignment rig for a four-wheel set-up.
A road test confirmed the knock was gone and the front felt tight again.
The outcome
Knock gone over humps, no rattle, and the alignment back in spec, so the front tyres will wear evenly again.
The Jetta went home feeling tight at the front. The absorber linkages are cheap parts, but left loose they cost real money in tyres and let the handling drift, so a fresh matched pair and a reset alignment put it all back where it belongs.