didn't see this originally. It looks to me that approximately 1/4 of the circumference of the valve seating area is not making contact with the seat. Several reasons for this. Lapping is a good first attempt to addess it, but it could also be an issue with the way the seat was ground. No gaurantee that lapping will address it, as that is taking off a microscopic layer of metal and really only works if the issue is debris or VERY small imperfections. Is this the first borescope? Would be helpfull to know if this just showed up or has been around since the beginning. my first guess is that the seat was ground with the tooling slightly off parallel from the guide (not tightening the pilot stem enough).
Insert the scope through the other plug hole and try to get a look at the seat contact surface. You should notice a distinct difference in the look of the contact area where the valve is not making contact vs where it is. If you see a chunk of debris at the center causing the gap, then lapping should clean it up.
Larry