Yeah, it's that aberration "up" in the 10 ns point I can not eliminate. I didn't think it was the cable. I generally observe the "dribble up" phenomenon. Do you think is the cable ?
I also have a 7A16 (not A) but I don't think it has that reflection. Maybe because of the smaller bandwidth?
Anyway, now the response of my 7A16A is much better than before. Initially was horrible. I think the previous owner tried to calibrate it but then gave up.
Really a tour de force: more than 4 hours fiddling the pots!
What do you think about the trim pot not shown in the schematics? May it be the very latest revision? I did not find more recent schematics.