Weed Eater One

I just purchased a weedeater riding mower from Home Depot. The plunger device necessary to raise and lower the blade mechanism will not work. If you ghegt on your hands and knees and push on thelittle silver detent, you can make it work until the next time. WHO wants to get on their hands and knees each time you need to adjust the height. Is there something I can do? Bill