I just noticed that there's a building tip from a guy named Gary. And he mentions the servo horn rubbing and servo savor touching the aluminum block.
"Page 22 A28, here is where you have to watch out a couple of things. If you follow the instructions and use the 1mm spacers between the servo and the mount, when you use the supplied servo horn as you rotate the servo, watch out for the clearance of the screw head to the carbon fiber support. This will be dependant of what brand of servo you use, but if you don’t adjust for the clearance it will rub thru the sweep of the horn. I ended up using a 1mm spacer inside the horn to get a little clearance, but also managed to strip the horn on a harder crash. Now if you use a servo saver, you’ll also have to trim it down so it’s a little narrower as at full sweep of the servo the saver will hit the extreme right side of the aluminum mount, and full lock will not be possible. "
And I complained about this w/o knowing this article exists. As beautiful as the serpent manual is, I wish there was a bit of written explanation. Sometimes it's hard to understand things just by seeing pictures. It may be ok to you experts but it's not ok to mediocres. lol