The photo of the horizontal stab under number 9. shows a square slot. Now that's where I stopped and should have read the note:

9. Open the horizontal stabilizer mounting slot in the rear of the fuselage with a sharp hobby knife (Please note-The elevator slot for the MKII is shaped like the stabilizer airfoil).

I'm guessing that the image is of the first version for the manual.
It's a toss up right now on either the Sequence or the MkII for me. I've opened the box of the Sequence and that is one very nice ARF. I consider myself somewhat critical as I've been building for over 40 years which the building part has been the most gratifying. I really love how the new planes are so much lighter and responsive, just outright fun to fly, but they just don't hold a candle to a mirror smooth body, and smooth flying with a to die for finish that some of the old master's pattern planes of 30 years ago. Not to mention the quality of construction and finish on the Formula Ones of that time.