Some builders have reported that they think the plans location of the servo causes a misalignment with the trim tab horn, so I set everything up as best as i could before actual assembly to check it. (Photo 1) First I drew the location of the inboard and forward edges of the bottom flange of the outboard bracket on the cover per plans, then taped the cover in position on the opening of the elevator skin. Next I just rested the servo/bracket assembly in place using the marks. Next, I clecoed the two trim tab horn halves to the trim tab skin and marked the centerline of the horn on the inside of the forward edge of the horn. I then aligned the trim tab skin with the elevator skin per plans, and taped it in place.
To check alignment of the servo with the tab horn, I laid a straight edge between the center of the clevis mount on the servo, and the horn centerline on the tab skin. Even though the servo clevis attach point sits slightly inboard of the center of the wide forward portion of the slot, the straight line between it and the elevator horn (path of the actuator rod) intersects the center of the aft end of the slot. I think I'll follow the plans on locating the servo...
Now that I had determined the proper location of the outboard bracket, I had to locate the inboard bracket (Photo 2): Step 1: I first located and drilled the outboard servo bracket to the servo cover per plans (the two 3/32 clecos on the bottom of the assemby). Step 2: I clecoed the servo to that bracket and the inboard bracket (the four 1/8 clecos). Step 3: I clamped the outboard bracket to the cover (the two cleco clamps). Step 4: I removed the servo and the outboard bracket to gain easy access to the flange on the inboard bracket. Step 5: I drilled the inboard bracket to the cover. Result: Fits perfectly.
I also deburred the servo cover and bracket, but will wait to scuff and prime with the trim tab parts once they've been final drilled.