That is where Tweaking comes in.

Though alignment is critical, C Band is very forgiving, just being close, you will get a signal.
What I do is just Eyeball it first: Loosen the Actuator Arm Clamp and slide to what looks to be the highest point. Set the Declination angle.
That will be the Challenge, as there is not a C Band Signal until 87 west.
What about Brasilsat at 84? That would be pretty close, are there any strong signals coming from it, there sure seem to be a lot of channels.
I have the probe on the old lnb at veritcal, at least I think so. So I am going to try to find some vertical signals before I change the lnb. I hope it is still good, I think one thing at a time would be the best way to go.
So I would rotate the whole mount, not drive the Arm, and find 87 West. Make a Reference Mark on the Mount and Pole. Rotate whole mount to the East, back to 83: on a 3.5" Pole, that is about 1/8". Recheck for Plumb, and Main Axis Angle.
Depending on your Arm Setup, mine is on the Right Side, when at the back of the BUD. Setup Receiver for the farthest West Sat as you can get. Retract the Arm all the way, then drive out a little, 1/2" or so, then slide the Arm in the Clamp until your far west Sat pops in, tighten Arm clamp. Now an Arm is not Horizon-To-Horizon, when setting the Sat to the East of you True South Sat, becarefull!!!! The Arm can extend and hit the mount. Set the Physical Limits too!
I have not changed anything. The dish was set up and used only about 7 miles from my home, so I figure the elevation and declination angles should be perfect. And I will not change the actuator mount until I see if I need to, hopefully, it will be perfect too.
Just an FYI: I'm at 88west, and can get from 43 west to 139 west with a 24" arm, that is the Absolute Max for my 10' Unimesh.