This solution was posted in another users topic about the same issue and it works.
The circuit boards inside the subwoofer contain the capacitors that need to be fixed.
You need to purchase the 470uf 35v replacement capacitors qty(2), which you can do at Radio Shack-catalog #272-1030 $1.33
You also need a soldering kit, Radio Shack also sells these for 7 bucks (i recommend the 5 piece kit).
After you get the goods; remove the back plate of the subwoofer and disconnect the power wires, unscrew the circuit boards and look at the pic below to find the 2 capacitors we are replacing:
Check youtube for quick and simple instructional videos for removing old soldering on circuit boards and applying new solder.
*IMPORTANT* Make sure the black stripe line on the capacitor matches up with the shaded portion of the circle where you place the capacitor.
Once you are done reconnect everything and do a test to check if it is successful, it should be; it worked for me and i never used a solder stick in my life.