Well this might require some background, otherwise I may appear as a total idiot who should not touch cameras
Full-time photographer since 2006 (part-time prior to that). Body history D2x D70 D200 D3 D700 D7000 D5000 D800 D800E D4 Df D4S and very shortly I look forward to breaking (in!!!) my D5. I also run a studio of 4 Nikon photographers as well as a camera rental service so the amount of lens copies that have ran through my fingers (and is available atm) is likely in the hundreds, though not (yet) exceeding 1,000. Which means that statistically speaking, the local Nikon service likes me a lot.
D2x
After four days in the rainforest, with lots of lens swapping the electronics started acting randomly, soon making it impossible to achieve anything with the camera. 32 hours later a courier from El Defe brought in a replacement unit, this being my first experience with NPS global service network. Covered by warranty.
D70
My dislike for CF cards springs from two swapped card bays, user error ie. small dust/sand particle in the card bending one of the pins resulting in somewhat costly replacement. Canon to Nikon swappers may experience this more, as the cards are inserted differently. Not covered by warranty.
Any body
Rubbers. I really appreciate that Japanese legislation requires recyclability, but the biologically degradable glues used to fix the rubbers to the bodies is so bad that every single digital SLR Nikon body that I have used has at some point seen the body rubbers replaced. Likely this is due to mileage, as confessions over beers have brought to my attention that this is a pest shared also by Canon users
(Sometimes, but mostly not covered by warranty as the glue degrades after about 18-24 months of active use)
D800/D800E/D810
Mirror box misalignment. One resulted from Norwegian Airlines luggage crew's handling techniques, the other from a camera renter who had used a light stand spigot as tripod for the body. DON'T USE SPIGOTS for that tripod attachment! They are longer than the screws on the quick release plates and once they enter the body they will push things inside upwards until they put pressure on the mirror box, resulting in misalignment. 36mpix is very demanding and even slight box misalignments will show in your photos. Not covered by warranty.
Df shutter
My 11 month old Df shutter decided to give up during a series of long exposures, verdict was "covered by warranty" which made me sigh and smile loudly. Only Nikon shutter that has breaken down on me, and the back-up body (D4) is past 450,000
200/2G Nikkor AF-S breakdown
To any of you using your AF-S lenses in saltwater environments, I'd like to point out that the idea of covering your lens from saltwater spray is a very good idea. While it is covered from dust and spray, salt evidently can enter through any protection and while slow, the process will reach its goal after a few years (in my case five), resulting in a 500 EUR replacement of the AF-S motor and electronics.
17-35/2.8D AF-S breakdown
Started squeaking at age 5, squeaked more at age 7, broke down at age 9. Replacement cost I think was 380 EUR. Lens saw almost daily use for 9 years so that's understandable IMO.
58/1.4G AF-S repairs
Don't put the lens in your back pocket, kneel and listen to the sound of it dropping to the floor. It hurt me about 250 EUR
24-70/2.8G (earlier, non VR version)
While I really really really liked this lens because of its image quality, it was clear that the mechanical construction had a lifespan, which in very active use meant about 3-4 years before the mechanical tolerances started loosening, resulting in erratical and not up to factory standard performance. More importantly, given the very complex construction of the lens repairs always meant an 800-900 EUR trip which saw the whole lens assembly removed, a new inserted and the serial number updated. Now, repeat this process 6 times and you really understand better why the old one cost 1600 EUR (plus 800 EUR replacement repair) and the new one costs 2600 EUR. I would really really investigate in the history of any used 24-70/2.8G that I was buying (if I were, which I'm not since the 24-70/2.8E VR seems to have rid those issues given the all new mechanical construction). This is not just my experience, ask any press photographer house and they'll verify. The Canon version suffered from the same issues (first 24-70/2.
, so no joy for the other side in this case either :-D
D810 USB 3.0 port
FFS this must be the crappiest engineer solution ever for data transfer. Why can't all Nikon DSLR bodies use ethernet/RC45???
In one week, I broke two D810 USB ports (420 EUR repair cost each) and why? Because that damn male connector is VERY prone to developing ONE single VERY SMALL pin misaligned, resulting in breaking the camera connecting port. The damn thing won't hold when you shoot tethered free-hand either, and the factory provided plastic strengthener is designed for MICRO USB3 connectors, when EVERY SINGLE ONE of the tethering cables use a connector housing too large for it. USB3 must be the shittiest connector ever, and while the design is not Nikon to blame I really really really don't understand why they chose it as the connector for their DSLRs, when a very reliable RJ45 (ethernet) connector is faster, sturdier and more reliable.
50/1.2 Ai-S
I have (had) a total of five, and they all were very different (some bought new, most used). With lenses focusing by moving the whole lens assembly, it really is recommended that you have their infinity adjusted. After a 90 EUR CLA they all performed identically: very well.
Any body and the diopter rubber
FFS why doesn't Nikon sell that spare part ie only the rubber ring? I have lost count on how many bodies I've handled with strap on my shoulder and that diopter ring rubber tearing off.
Interestingly, the plastic focusing switch ring AF/M on many pro-series D lenses seems to be very prone to breaking. I have never experienced that (knockknock), though I have many of the lenses equipped with that unpractical AF/M switch.
Anything else... hmmm. Oh yeah: If you happen to be a member of the about 2,000 persons globally that own an 800mm f/5.6E FL VR lens, DON'T MISPLACE THE DEDICATED TELECONVERTER. I haven't, but a colleague of mine did. You have to send the lens back to Japan, wait about 2 months for them to assemble and adjust a TC dedicated for your lens copy, and see your lens returned with a new teleconverter. Total cost? While pressed when I asked him he did not admit it but I got the perceptions that it was in the range of 2000-3000 Euros