Mute button is sensitive and vibrates occasionally

Hello!

I'm unsure of the error in my iPhone 3GS.

I have a problem with the vibrator, it is very sensitive!

When I gently touch the mute button the phone will vibrate. Squeezing the phone lightly also starts a vibration.

When I have the phone disassembled, I notice that the vibration occurs immediately of the slightest touch back of the "Jack Flex Cable" (where the mute button switch is located). Link to picture at www.ifixit.com...

http://guide-images.ifixit.net/igi/GvUtY...

You see those two gray plops above the red markings? When one touches there lightly it vibrates. The most sensitive spot of them all!!!

After assembled the device again it got even worse and vibrates when ever it feels like.

My question is...

What part needs to be fixed?

Is the vibrating motor over and out? or is it the "Jack Flex Cable" that must be replaced, what do you believe?

Thanks

Krall