7D2 is not sharp at wide end with 100-400 II

One of my two 7D2s is not sharp at the 100mm end when I shoot with my 100-400 II. It seems to be fine at the 400mm end.

I know it is not the lens, because a) the lens was just checked out by Canon and, more importantly, b) the lens works perfectly with my second 7D2.

The "bad" 7D2 does ok with other lenses like my 500/4 II.

Have you guys seen this before? I am wondering if I should take it in to Canon to get checked out. I mean, I can avoid pairing the "bad" 7D2 with my 100-400 II, but I'm kinda picky about this sort of stuff and hate knowing that something's amiss and living with it.

have you tried micro-adjustment on the camera at the 100 end?

Yeah, I forgot to mention. Yes, I did MFA using Reikan Focal. It gave me a value of -13, but the sharpness is still not there. The value is -1 at the 400mm end. The large number isn't giving me good vibes either. I might just have Canon take a look at what is going on.

Yeah -13 doesn't sound good. Must be something else going on.

I went back and took more shots and maybe things aren't quite as bad as I feared. It seems to be more of a compromise, as the "good" camera isn't as good on the "bad" camera on the telephoto end, although I am nitpicking at this point.

After shooting a bunch more shots, it seems like the differences, while there, are within the margin of variability, and I can make the "bad" camera do better than the "good" one at the 100mm end by breathing at the wrong moment, etc., which may be what I did earlier when I was concerned about how the "bad" camera was doing at the 100mm end.

So, I'm going to let things be - I have tweaked both cameras with Focal with multiple repeats to average out any error. While the MFA values are relatively high at the wide end, -13 for the "bad" camera and -7 for the "good" camera, I am pretty confident in the results. The Focal fits are very good - I have attached the graphs for reference.

"Good" camera at 100mm:

I assume you have IS on to help prevent any of your movement during the adjustments? Also, I have to assume there are no filters on the lenses.

Yes, I don't have any filters. My camera is on a tripod during the adjustments, and Reikan Focal specifically wants IS turned off during the data acquisition process.