Probably you have a bad trim limit switch (port side gimbal ring). The trim limit switch makes a connection when the drive is low, to get it up higher the two buttons are used to bypass the limit switch. Note the Blue and Purple wire feeding the switch. Find these wires back by the drive, and pull the connectors apart. Now jumper the Purple and Blue wires going back to the switch (not going to the drive). Once jumped, the trim up should raise from full down to full up
