I sent in two D600s for shutter repair. One was a refurbished D600 and the other was purchased new from B&H. Both were spattering something on the sensor and both had been in for a sensor wet-clean at Calumet AND Nikon.
I sent in both bodies to Nikon after receiving a quasi-recall notice in my email from Nikon. Both were sent in around March 20th.
The bodies were returned on 4/7 with a invoice repair slip noting:
1. Replaced shutter mechanism
2. Related parts
3. Adjusted auto focus operation
4. Checked bayonet mount
5. Clean image sensor
6. General check and clean
Total amount due: 0.00
No D610 (darn) but both bodies are working fine (so far).
I should note that the refurb D600 was purchased from Adorama some 8 months ago. It's technically out of warranty but kudos to Nikon for taking it for repairs, no questions asked. (my)