Fixing 5D II lens mount issue, experience?

[extremeinstability]

Or any camera.  Just wondering any experiences people have had sending in their camera to fix/tweak the camera's flange problems.  For instance I had a 24L from lensrentals that showed issues and wound up swapping it out for a 21 Zeiss, which is showing the same problem.  In short it's clearly my camera that is the problem and I guess canon can fix it.  With those lenses on my 5D II at infinity(manual live view) the left side pays pretty hard in softness.  But focus them inside infinity much and the right side pays badly.  Before sending it off and giving them $200 I'm wondering how well things change.  Knowing how I do things, I'll get it back and it will be doing the same thing. 

It is crazy how much this is affecting that focal range.  Takes about F6.3 on the Zeiss to get its left side to where the right side is already at at F2.8.  Not sure that was even getting it there.  I'm also just wondering how common this is for people to even know to need fixing.  Bet the lens gets blamed a lot more often than it should just over this issue. 

Here is an example with the Canon 24L.

http://www.extremeinstability.com/24.jpg  full frame
http://www.extremeinstability.com/24-3.jpg  side crops F4 focused about the porch or backside of tree(was trying to use something in the center)
http://www.extremeinstability.com/24-1.jpg  focused infinity on the roofline you can see it swaps sides.

[CharlieB]

This gets into a bit of a sticky wicket.....

You must have alignment of the lens mount to image sensor. 
Lens mount to mirror.
Mirror to image sensor
Mirror to focusing screen
Focusing screen to image sensor
Mirror to AF sensor
etc etc etc

Canon can fix it, but it might not be the lens mount.

Never aligned a digital body.  Have aligned Nikon F's, F2's, Canon F1's.  Its a pain.  A real pain.
Sure with the right equipment... its not that bad, but outside of factory conditions... its a pain.

[extremeinstability]

Thanks for the reply Charlie.  Canon has a flat fee of $219 so they say on the phone to fix a 5D II.   Wondering if when they got it, if they'd even see that it was already meeting spec and charge a whole lot less, or more likely just tweak it some amount to charge that anyway.  Managed 10 years now without ever bothering to send anything to Canon.  Funny I bought the thing used very recently for $1500 thinking it made more sense to do so and save a few bucks towards lenses.  Now kicking myself since I'll be at the price of new now anyway.  If only it were less off I'd just live with it.  But kinda pointless to fork out bucks for like the Zeiss 21 and have the camera flange to sensor plane screwing it all the hell up.  Least I established it's in the cam.  Guess I'll send in the 10-22 and have it cleaned and autofocus fixed just so I can sell it to help pay for the 5D to get fixed lol.  I guess my biggest fear is it coming back mostly with the same issue, maybe just improved a little bit or changed its behavior at one focus distance or another.  Guessing I should at least stick the 21mm Zeiss in there with it and say at least get the left and right side to match with that lens on there. 

Anyway thanks for the thoughts.  Surprised more haven't had this done, sorta.  I bet it's a common reason people's 'lenses' seem off all the while them never even knowing it could be the body's mount to sensor.  Pretty darn certain the T2i I have is off in the same exact way.  The mount over a couple years of use with heavier lenses probably often gets pulled the same direction, or something.