What is wrong with my wipers

First pop the covers up on the pivots. There's a 15mm nut on each arm. Put the arms in the proper position, then snug the nuts.

If both arms move together and stop at the same time, check for a linkage popped apart. You'll have to remove the arms and the plastic cowl screen to access them. If a linkage pops apart again, replace it. That's easier than trying to find the nylon inserts and installing them.

If one arm moves freely and there's lots of banging going on, the lever likely broke off the pivot. That seems to happen more on the driver's side. Remove the pivot, tap the arm back on, then quickly put a small tack weld on it with a wire feed welder. You have to do that fast enough so it doesn't melt the plastic. Originally that arm was just pressed on. Don't worry about lining it up or orienting it correctly. Once installed, there are so many fine splines that it's easy to align the arm onto the pivot.