NCS is sometimes heavy handed, but they can also do gorgeous work. I would not ask for conservation on a toned coin. You won't be happy with the results. You should be conserving every coin you submit yourself to ensure there is no residue.
I've had similar problems with them, once sending a Mint-State 1945 Micro-s FULL bands Mercury dime, where they missed the Micro-s and bands. A return and they missed all bands being complete across the Fasces. I didn't attempt a further, or any future action. There's a reason why generally a premium is charged for a PCGS same date/mint/grade certified coin from a dealer selling both. Collector Beware! JMHO
The best grader is YOU. If I buy it graded okay but if my eye appeal takes me to a coin, I'm the best grader I know. My money, my choice, my grade! Sorry for your inconvenient loss. Thanks for sharing. Top 3, top 10, top grading company, none are worth the effort in my opinion.
That is just so sad. I feel awful for you. I think I'll reconsider using NGC. I'll probably still purchase slabs that they have graded, but I will refrain from them grading my coins and definitely would not have them conserve any coin.
I have a beautiful 2009 silver proof set from the UK including the famous Kew Gardens fifty pence it is in original royal mint packaging and I was told by a newbie that the Kew would be worth more if I had it graded and slabbed. People are being brainwashed into parting with their hard earned money by the grading companies into believing that their coin is only worth more money after they have paid them to grade and slab it. I assured the young chap that to break a silver proof set from its original packaging is tantamount to heresy and people who do so should be horsewhipped.