This is pretty common, if the replacement part are not available from the factory, since the next largest assembly is usually replaced, not the defective part. Manufacturers across the board are limiting stocks of parts for older models whether cars or TV or cameras. Camera electronic repair is way beyond the component level repair capabilities of camera service departments so only larger assembles are stocked. The factory shop probably has rules about only using new old stock parts, of which there likely are none in the supply chain. An independent can attempt a component level repair or use a used part that is not allowed in factory shops.
Years ago I bought a Sony PCM3324 reel to reel tape deck that was $125,000 in 1985 money or about $400k now, plus the remote controller for $22,000. 2 years later they release updated version and stopped production of my model so based on their company wide policy, remaining parts prices were increased 10x over night and another year, stopped stocking any parts. Many parts are wear items that needed replacement from normal operation. So suddenly my investment was worth almost zero. I never bought any Sony product again and discouraged others from buying them. My Swiss made Studer 24 track analog tape decks had new stock parts available for a couple decades. When Studer was purchased by t Harmon , a US holding company, they dumped all the spare parts for older models so killed off their customer loyalty. Few companies support products like they did when they were intended to be long term purchases, now that everything is considered throwaway.