Document what has changed
Look for gaps along the perimeter, low spots that hold water, uneven vehicle paths and cracks that appear to be changing. Note whether doors operate normally and whether the movement is confined to the slab.
Separate slab issues from structural concerns
A garage floor is not necessarily the same element as the foundation. Movement involving foundation walls, significant structural cracking or other building components may require evaluation by an appropriately qualified professional before any slab-lifting decision.
What a leveling assessment considers
The contractor should evaluate slab integrity, access, likely voids, desired elevation and the relationship to walls, drains and the garage door. An apparently simple low spot can have constraints that are not visible in photographs.
When another repair may be needed
Extensive deterioration, unsuitable support or a need to reconstruct drainage can make lifting inappropriate. Ask whether the recommendation addresses the cause or only the symptom.
What to mention on the call
Describe the age of the observed problem if known, the location of cracks, any water entry and whether the slab is next to a foundation wall. Do not rely on a phone conversation alone for a structural diagnosis.