I can't comment with any authority, as I've never had a warranty claim on any reel - and would just handle any such repair myself. I'd rather just buy the parts and do it myself, rather than pay two-way postage and wait months for someone else to maybe get it right. Basic maintenance is easy, but I've been doing it for myself and others for more than 50 seasons, so there's that.
It is a common misconception that reel manufacturers keep deep parts inventories, going back decades. The only one that I know of (from personal experience) is Abu-Garcia, in Spirit Lake Iowa. And even they appear to have trimmed their inventory, sending much of it to eRplacementParts.com.
Penn is O.K., but for example previous to the re-introduction of the 704 surf reel, many of those reels had to be retired as the parts for the original (like the anti-reverse mechanism and main gear) were discontinued, with no replacement. I do not know if the current 704 parts fit the originals, never having had to source any.
Shimano and Daiwa openly state that they keep inventory for older/discontinued reels for 10 years. After that, availability is spotty at best. Most reel service departments will not take on the servicing of a reel for which they no longer stock parts, so that's probably what happened to your friend.
There are alternatives for service and the sourcing of obsolete part. Like I previously wrote, ereplacementparts.com is one good resource, but I find Ebay to be my go-to for this purpose. For example I have an original Shimano Curado CU200P that I was forced into retiring years ago, as the gears were shot and I couldn't find a fresh set anywhere. About 6 months ago I was meandering around Ebay, not expecting much, and for sh!ts and giggles gave it a quick search. Lo and behold, one guy had a brand-new set of the exact 5:1 gears I needed for that old reel. After years of searching I couldn't believe my eyes, and had to check the part numbers twice to be sure. Cost me $50, but I am now able to put that $170 reel back in the rotation, and in fact I'm looking forward to using it this coming fluke season. "Old friends" can apply to tackle too, not only people. At least for me anyway.
For Daiwa and Shimano parts there are several sources that could help, Southwest Parts, is one, as is Dave's Reel Repair. Both have had some discontinued parts I needed to complete some of my friend's repair work.
Of the local shops, Causeway is (or at least was, last I heard) a Daiwa factory-authorized repair center, and Trophy has my favorite resource - Gregg the reel repair expert, formerly of Causeway, he is the one I ask for advice when I run into a very tough job. You can trust either of them to do the right thing.
