[kerneltugboat]

They will stick if the surface they are mounted on is not PERFECT (I actaully had fiberglass backing plates made for mine) , and they should be tightened doen from the center-out. I calibrate mine at the beginning of each season just to be sure. I think you hold down the up and down arrow, apply power and keep the buttons down for ten seconds? then they extend all the way out, and all the way back in automatically and you are ready to go. I am going on three years with no issues after the inital install. they work great on my 27, they must really be sensitive on a 23 or a 21, i paid about 600 bucks for mine.