Companies are run by people who drive spreadsheets for a living. It's neigh on impossible to place a value on a historic aircraft doing loss-making sightseeing flights.
I sympathise with the cadre of old hands who kept the aircraft going, as well as the new generation of mechanics and pilots who they taught to fiddle with something that's not run by software and microchips.
Count myself luck I had a chance to fly D-AQUI many, many, moons ago as a 'thank you' from Lufthansa Technik. They'd move the operations from FRA to TXL (or vice-versa, can't recall) and had lost the PW engine manuals in the process. As a young sprog I was sent to the basement of the company I was a trainee at, to see what I could dig out. Found both an original engine- and parts manual, both of which were professionally copied and bound in leatherclad binders, then sent free-of-charge to a very grateful Lufthansa.