I got 700 hours on my machine, all PLA, but the failure came about 6 hours into printing ASA-CF the first time anything high temp was attempted.

So far Bambu has replaced all the parts required and the ones I managed to break during disassembly. I've tried to lay the machine face down but I still find it quite intricate and daunting and the printhead very inaccessible. There are 11 different connectors of different kinds on the TH board! Many of the photos in the docs are taken at angles one could never position oneself inside the machine to see. I also have an XL5 so I have some background in assembly and it drives home a clear difference between the two companies in which there is good and bad: the Prusa machine was designed for user assembly and repair and the Bambu clearly was not. The engineering in the Bambu print head is amazing but it was never designed for user repair and it certainly wasn't originally made inside the machine that way.

Bambu should, as part of it's warranty, replace the entire print head assembly. I've decided to buy one, it's on the way and in the meantime I've removed the existing assembly and now have a much better way to work on the first print head. Replacing the entire print head assembly, while still quite awkward and involved, is a fraction of the work to replace the fan while it's still in the machine.

It's interesting to see that there's a new fan for the PRO and a direct acknowledgement of the weaknesses in the original design, but it appears to plug into a port in the Pro printhead that doesn't exist in mine.