Mark the final position for the tray with a Sharpie dot on all 4 corners I used Silicone to secure the tray to the fuse. Use Goop or Silicone. Don't use CA or Epoxy a flexible joint is much better here. Have your elevator servo(s) in the tray so you know the proper height of the tray. For single servo installations this Expert SL451 servo is a good choice: It's fast, has 48oz torque, low profile and costs about 25.00. It's the same size as a JR DS3421.