First, I will say I love the lens. Amazing sharpness on all my cameras. I use it primarily on the D500, Z9 and D6 use it also. Great photos, value priced, highly recommended.

The concern, the lens locks the zoom function. Mine locked at the 500 position, so I used it as 500mm lens, which I did not need as I have the 500 f4VR and 500PF <==(wow, what a lens).
When the 2nd lens locked (I had another that locked too). I took it to a friend who used to own an authorized service for Canon, Nikon, Pentax and likely more. Although now retired He agreed to work on it. Below is a detail of this and that followed by the cell phone images I made (this silly photog forgot to take alone a dslr>>)

Repair of the Nikkor 200-500 f5.6

I had my 200-500 F5.6 fail with a screw coming loose in the zoom set. This happens often; sure you have heard of it. Nikon suggests 480ish dollars to repair, but the lens may have more damage depending on what the loosened screw contacted. Plus insured shipment each way, add $50. They also said they had 20ish ahead of me so it will be 15 days ‘in house’ repair.
I contacted a retired camera service center owner, who used to be a warranty authorized repair center for Nikon, Canon and Olympus. He is located 45 miles north of me. Claude not only recalled me he recognized my voice and ask if it was me. This was after 15 years since we last talked. I detailed my lens problem. He did not even know Nikon offered the 200-500 lens. He agreed to take a look and save me the shipment and wait hassle and price of Nikon repair. I watched as he disassembled the lens. Amazing parts within, tiny electrical wires and connections abound.
On to the actual concern: There are 3 or 4 (can’t recall) channels cut into and rotating within the barrel of the lens. In the channels are a tiny screw, nylon sleeve that move within the channels of the lens to extend and retract as we zoom the lens. The screws on the fixed nuts come loose in time and one will abruptly come out and lock itself within the channel, locking the lens from zooming.
He shook, pulled, begged, twisted, and on and on until the screw finally fell out. He removed the barrel and cleaned all the parts. Disassembled the other tiny screws, nylon sleeves, more parts and cleaned all. Reassembly he added a teeny tiny super small speck of thread locking to the screw threads. The locking fluid does not actually ‘lock’ but does slightly firm. He explained he always reassembled lenses this way, and acknowledged that Nikon will not use any liquid firmer as the assembly person may over-use and eventually a speck will get loose and adhere to the glass or something else. He is carful and does not over use the goo, so no concern.
Claude said that unless Nikon has changed the way this lens is made, EVERY LENS WILL FAIL, PERIOD. The effort of the in and out motion as we zoom the lens will cause the screws to release and fail the lens. Most lenses that use this type zoom, move fast thru the short travel, while this lens takes a couple grips and turns to travel the heavy 200-500 zoom action. Recently this lens has become hard to find, stock is low or out. Maybe it is because Nikon is revamping the manufacture procedure of this lens? Be sure to save your receipt, warranty absolutely requires it. Even if you have lost it via a move, fire, storm, flood, divorce, and so on. No excuse accepted, receipt absolutely required.
BTW – My lens is smack on perfect! So smooth in zooming, he adjusted the centering and focus (as Nikon will too). $234 out the door. The lens is actually sharper than before failure, he perfectly centered the elements.