OK, this just started about a week ago. The wipers worked absolutely fine before.

They've started doing this thing where they like.... jerk across the windshield. Almost like they're sticking. I haven't seen them do this on the UP stroke so far. It's like it only happens on the DOWN stroke. It seems to happen RELIABLY if the windshield is dry or very nearly dry. If I use the washers, the first stroke seems ok and once the windshield is cleared the second stroke jerks down and parks but it appears to do a little "stutter step" as it parks.

It APPEARS like as if any resistance at all causes this jerking. I turned them on in moderate rain and they seemed to not do it ... just an intermittent problem or was the water making them slide easier? I don't know.

So... in a light mist... it's brutal. It looks like something is going to break.

What can I do to troubleshoot this? What should I be looking at?

 

A common problem for the x-type is the nut on the end of the wiper motor loosens and starts causing movement problems. If you remove the grilled area and the wiper arms you can access the end of the wiper motor. The wipers can be removed by lifting up the hinge cover where the wiper mounts and removing the nut. You will need a small puller to release the arm. You can then remove the screws holding the grill work and access the wiper motor.
If you find everything tight you can do a search for "wiper motor" they can get gummed and and there are a couple of postings for cleaning it out.

 

Following up on this...
Pulled the car out, turned wipers on, ran ok for a few strokes and started to "stick".
Stoped them
Raised the hood, and then got back in the car, wipers to "on" position, jogged them around using the key. This exposes that nut on top of the wiper motor.
I actually have a this, flat, blade type wrench that fits that nut exactly. It's used for changing blades on my circular saw.
I was able to slide that wrench i and get it on the nut and..... nope... that nut is tight as a tic.
Left hood raised, turned key to ON and watched wiper motor. When the blades started sticking, the motor and that tubular thing it's mounted to would move as it was being torqued.
Lowered hood, lifted blades off windshield in their "stay outa my way" position.
Smooth as a baby's bottom. No jerking. Put some finger pressure on one blade arm to see if I could make something slip. Nope... can hear the motor strain a little against the resistance I applied, but strong and smooth.

So...
Stopped the wipers. Got some rubbing alcohol and a terry towel and cleaned them. Cleaned the windshield with regular glass cleaner.
Wipers back onto the windshield, turn on...... no sticking.
There's still a lot of drag. I can ... see it... if I spritz a little water on the windshield, the wipers speed up just a bit. Makes me wonder if A.) these "high performance" wipers are TOO soft... or B.) Is the arm pressure on the windshield too high? I don't have a spec for what that pressure is supposed to be, nor do I have a way to measure it. Can auto parts store do that? Or would it have to go to a mechanic?
These wiper blades are maybe 2 months old... or 3.... and this just started happening. If I change them out again, it won't be for this type, even though they do a great job. I can't see where putting noticeable drag on the wiper motor could possibly be good for it.