SUMMARY AND UPDATED (8/20/16): THERE ARE TWO FIXES OUTLINED IN THIS THREAD.  ONE IS TO REPLACE DEFECTIVE CAPACITORS, AND THE OTHER IS TO CLEAN UP AND REMOVE THE CONDUCTIVE "GOOP" THAT'S SLATHERED ALL OVER THE PRINTED CIRCUIT BOARDS.  BOTH ISSUES RESULT IN CRACKLING AUDIO, STATIC, POPS, LOSS OF BASS, AND FADING IN/OUT SOUND.  HOWEVER, IT SHOULD BE NOTED THAT SIMPLY REPLACING CAPACITORS MAY NOT BE ENOUGH TO REPAIR YOUR SPEAKERS TO GOOD, OPERATING CONDITION.
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Crackling and Static Sound - CLICK HERE - What does it Sound Like?
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I purchased a pair of KRK Rokit 6 powered studio monitors back in January of 2012 from Guitar Center. Because of the nature of the equipment, I purchased the 2-year, extended repair/replacement warranty.  It was only $50 for better peace of mind. But wouldn't you know it, 10 months after the extended warranty expired, one of the monitors starting failing!  Now isn't that typical?!?  Upon power-up, one of the drivers emitted quiet crackling and static.  It sounded like when a dirty pot is rotated or an audio plug is wiggled/twisted.  Sometimes, this static and crackling would subside and not return, as if the monitor had "warmed up."  However, it wasn't until the crackling and static didn't go away that I decided to take action.
 
I am very familiar with board-level components, troubleshooting, repair, circuit design, soldering, etc. It's what I went to college for and up until a few years ago, I made and shipped original, audio and computer mod devices all over the world. My real job, however, has nothing to do with circuits and repair!  Haha!  But enough about me, let's talk about fixing these speakers!  Considering that most audio repair shops (if you can even find one), or the manufacturer, would most likely charge an exorbitant amount of money for the repair/replacement, I decided to put together this little "how to" guide for the benefit of the community.
 
• Skill level: easy; anyone can do this repair
• Tools Required: Philips screwdriver, precision snips, soldering iron ≥40W, desoldering braid, 63/37 solder (the good stuff) or lead-free solder, and of course the components.
• Components Required for This Particular Repair: 3300µF, 50V electrolytic capacitors (I chose part ECA-1HHG332 made by Panasonic, labeled as "audio grade," low ESR capacitors); and 2.2kΩ, 1/2W carbon film resistors (direct replacement to existing resistors).
• Cost of Repair: $10.85 (w/o shipping); I got enough components to repair both speakers.  All components ordered from Digi-Key. (My stock of a bazillion parts did not have such large caps and 1/2 resistors.  I have some 1W resistors, but not 2.2k).
 
Steps:
1. Turn monitor on it's side as shown and remove the 8, Philips pan-head screws around the perimeter of the backplate.

 
2. Take a small flathead screwdriver and pry the backplate from the cabinet.  Drop it down to the table.

 
3. Check out the capacitors and the resistors for trouble.  I've included pictures of the particular trouble that plagued my speaker.  NOTE: KRK put this awful, crusty black goo all over everything on the amplifier board. Basically, it's glue to hold various components and connectors onto the board, preventing vibrations from disconnecting or breaking them.


 
4. Essentially, the capacitors are used for positive and negative rails (±30Vdc) for the amplifier circuitry, perhaps in an AB class design.  The bulging capacitor means that it has failed.  The dielectric either dried out and/or the rail voltage exceeded the rating of the capacitor, causing it to fail.  In my haste, I did not pre-measure the failed capacitor's voltage while powered on.  This would have been a good tidbit of information.  However, I surmise that the root cause of the failure is the capacitor, which caused a high leakage-current which in turn raised the rail voltage thereby causing overheating of the 2.2kΩ.  Whew!  Anyway, we gotta get these garbage components out of here!
 
5. Rotate the backplate counter-clockwise into the cabinet, being careful not to overstretch the wires.  You could disconnect some of the leads, but why bother.  The goal here to to access the solder side (back) of the amplifier board.

 
6. Using the soldering iron at the highest setting and the desoldering braid (with a little flux), remove the two, 3300µF capacitors and the failed resistor(s).  I chose to not replace the resistor that was OK.  No reason to do it.  The capacitors, however, are crappola and need to be removed regardless of how they look!

 
 7. Here are the nice, new components:

 
 8. Install and solder the new components to the circuit board.  Hopefully you noted the orientation of the capacitors before you removed them!  Either look my pictures and/or note the silk-screening on the component side of the PCB.  Here are the new components soldered to the board.

 
9.  Reassemble the speaker by reattaching the backplate.  Do not not overtighten the 8, pan-head screws as the speaker cabinet is made of MDF.  The material is soft and the screws can strip easily.
 
10.  Test the speaker to see if the trouble is gone.  In my case, this fixed the crackling static!  Suh-weet!
 
I know the Cakewalk Forum is a little light on this kind of stuff, but I hope this is helpful to anyone finding themselves in need of such repairs.  Thanks for reading!

Nice one! Capacitors are always the first port of call especially in much older equipment than your krk's.

Heh, had to replace capacitors in my 30yro Yamaha M-80 audio amplifier once - still have it. The old bugger can do 30W in class A mode, which is really more than plenty, or 160W class AB...

Excellent post on repairing your speaker.  Can apply to others, as long as there is physical evidence. 
 
I used to do amp-repair (in Nashville) and wouldn't attempt anything I didn't have a schematic for.  Sometimes you get lucky and find the parts, such as your repair, but for a repair shop you can't take the chance.
 
But, your detailed explanation gets a "gold star".

Thanks for the how-to! I'm completely ignorant when it comes to this stuff, so it's very helpful to see how it's done.

Yes excellent post! Funny those parts went south? I guess s--t Happens

Great post. I have KRK's. The V series though. Haven't had any trouble with them at all. But good to know this can be done.

That was a nicely presented project with good information and illustrations. Well done!

Good post Tony well present with good clear pictures and written instructions.

Wow.  These monitors are pure garbage.  The crackling is back, now worse than ever...and in both speakers.  I have recently moved, and I don't think they survived the trek across country despite being packed in their original boxes and Styrofoam inserts.
 
Back to the workbench!