What is " the beginning stages of failure"? It either has or it has not. If you can cee cracks (PT slab), It has failed. (Rebar - not neccessarily a big deal). If it feels out of level when you are walking thru - it probably is outside the allowable or acceptable tolerances - 1" - 15'. Most, probably all, residential buildings on/in clay soil will move. Masonry, moldings, gypsum may/will have stress cracks from the movement - That is not neccessarily a foundation failure. If you suspect excessive movement, get the elevations, or defer.
Do not automatically accept that a "new" foundation is ok.