Pallet lever changed in the service

What version of the movement is in this watch, and how old is it?

Sometimes parts are changed as part of an upgrade to the parts. So for example the pallet fork in the early 8500's is changed to the non-magnetic version, and the jewels would be changed also due to some issues the early anti-magnetic jewels had - more on that here:


So it's possible that these parts were changed as part of these upgrades. If you look at the jewels and they have that brown residue in them as you see in that thread, then you know that's why they were changed.

Having said that, I see a lot of photos of parts being sent back, and I see that more often than not both the pallet fork and co-axial wheel are being replaced. These are from movements where these upgrades would not need to be done, so clearly there is wear happening on these parts because otherwise they would not be replacing them. To look for the type of wear that would cause the need for a replacement, you would need to examine the working surfaces under a microscope.

Most of the upgrades I referenced were from that era, so more likely to me that this was some of the reason.