Help can't see

[piker]

My windsheilds wipers work sometimes but the problem is the right side does'nt go all the way down. they it starts to go more to the left these cause the left side to not go all the way down and on the up cycle it go,s more to the right until it catchs on the side of my truck ... Then I have to stop and push the wiper down all the way and they will work for about 20 times then start this cycle again need some help been raining alot here .