I recently tried deleting an object in the model tree which affected the proceeding constraints. Is there a way to restore the original constraints after unfixing the part locations or does this require re-constraining every part?
If the constraints are directly reference the deleted part, you will not be able to recover them without reconstraining every part. You can use the "edit references" under the RMB on each part to quickly re-select new references. Also, if some of the failed components are children of other failed parts, they will correct themselves when their parent is re-constrained.
FYI, Edit References is the chain looking icon, it's also under the model tab, operations drop down arrow.
Steve Williams Pro/E Version 15/16 (Circa 1995/1996)