Basically I think that Lionel Customer service is very good. In addition their network of Service Stations is very knowledgeable.
There have been comments from time to time on these boards that some individuals think that the product they sent to Lionel Customer Service in Ohio for repair is not the same one that they got back. In fact one poster noted that the Legacy set he sent out for an upgrade came back looking like it went through the war.
I have had a similar experience with an engine, PRR U28c, sent in because one of the number boards did not light up and there was a defect in the paint, the impression of the foam inner liner was on the top of the center portion of the shell near the cab.
When I got the engine back, the paint defect and the number board issue had been addressed but the front pilot was damaged, snow plow cracked, front railing chain damaged and the MU folding platform on the rear of the engine was missing including the retainer that holds the platform in place.
The product was shipped out to them in a larger outer box that Trainworld used with the original shipping carton and original product box inside protected by foam peanuts. When Lionel shipped the engine back to me they just shipped it in the Lionel shipping carton.
There was no indication that the box or its contents had been damaged in shipping. Everything was intact there were no dents in either the inner original box or foam interior or outer shipping carton.
Lionel customer service did replace the defective parts but I'm not convinced that the engine I got back was the same one I sent in for repair. I can't prove it other than that the engine I sent in for repair did not have these defects.
Bottom line, mark your products in several inconspicuous places so that when you receive the item back it is the same one you sent out. Also photograph the markings to prove your case in the future.
If they need to simply replace the engine rather than repair they should ship a brand new never run engine. Not one with damage.