Silent/lock button causes intermittent vibrate

Hi all,

Odd one; keeping the Silent/lock button in the off position seems normal. Once the button is switched to silent/lock mode it activates and displays the transparent logo with a line through it, meaning the mode is active, thats normal too. However, intermittently the logo will show again with a vibration showing its now off, and then again with a vibration to show its on again, this continues at random intervals and sometimes multiple vibrations and logo flickers.

Anyone had this before? - I've checked the vibration module but not the headphone jack flex assembly yet, just want to make sure I'm not missing something before I open up.

Quick bullet point summary:

• Vibrate/silent switch intermittently vibrates and displays silent logo once switched on.

• Vibrate/silent switch physical movements seem solid.

• All other buttons work OK.

• Headphones working OK.

Thanks!