Repair Work Doesn't Follow a Standard Routing
Most manufacturers already have a production process under control. Returns, repairs, and overhauls are a different problem. Every unit that comes back can need a different diagnosis, a different set of parts, and a different sequence of work, and that path isn't known until the unit is in front of a technician.
When that work runs on spreadsheets, paper travellers, or a production system that was never built for it, turnaround times stretch, warranty decisions get made on incomplete information, and the traceability that started on the original build starts to break down.
Common challenges include: