For most scratches that cannot be removed with SSR 2 or a similar product, I usually get out the 2000 grit paper and wet sand till the scratch is almost gone ... then I follow up with SSR 2 on a cutting pad either on a PC or rotary.
I feel there is safety in wet sanding because you can work in a smaller area and with more control than with a buffer.
If you feel that you are going to destroy the clearcoat before removing the scratch, then the scratch is a lot deeper than you think it is.
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