Windshield wipers different speeds

2000 Chevy Blazer.  The other night I turned on my wipers and the driver's side worked fine, but the passenger side only moved a little bit.  But with every cycle, it moved a little more, but not at the same rate. So after a few cycles, the two blades collided in the middle, and knocked one of the blades off.  I put new blades on but they are not moving at the same speed.  What can I do?
------------------------------------------------------------------------------------------

Windshield wipers are great for clearing the view when they work properly. But when they don't the view couldn't be more obstructed. Your windshield wiper arm retaining nut has managed to work its way loose. This happens more often when there is snow or ice build up. The windshield wiper gets frozen to the windshield. The windshield wipers get turned on and the motor is strong enough to loosen the retaining nut on the windshield wiper arm. This allows the wiper arms to move around and collide with each other. The wiper arm will need to be adjusted and the retaining nut fastened. Then they should work as they should.

Windshield Wiper Arm Replacement

Remove the cap from and retaining nut. I find a flat blade screw driver works well for removing the cap. Then you will need to remove the windshield wiper arm assembly. The windshield wiper arm can be difficult to remove. The use of a windshield wiper arm removal tool makes this job easy.  

Using the tool instead of a pry bar will save you from cracking the windshield. The tool is easy to use and dose not require a lot of strength to operate. Once the wiper arm is removed, set the wipers in the "OFF" position so they return the the fully stowed position. Note the position of the existing arm and match that when installing the wiper arm. Install the retaining nut and cap. Test windshield wiper operation.