Well this is not the best solution to your problem, it's only temporary!
Like I said, it's deffanitly NOT the best method and it's only a temporary fix, but I don't think any one should try it because it may cause it to be worse, or damage your iPod! So don't blame me if you make it worse because I warned you!
Ok well this always seems to work for me, but keep in mind my iPod is an old 3rd gen that's has been through alot. The washer, thrown around, taken apart to fix the head phone jack (which only made that problem worse, thanks big bro! Lol) and another big brother who is VERY rough with it.
It is a simple solution, but SEIROUSLY and I can't stress this enough only temporary, may cause damage, don't use unless EXTREAMLY DESPET.
Step 1 hit the damn thing on something hard but be very gental, like a table or desk ect. NEVER metal or concert!
Step 2 enjoy you newly "calibrated" iPod lol
Like I said always works for me, but lots of damage all ready.
If you do actualy attempt this then you welcome BUT SEIROUSLY DON'T DO IT UNLESS YOUR DESPRATE, AND DONT MIND DAMAGEING A SOMETHING HUNDRED PEICE OF STEVE JOB'S (may he rest in peace) FINE HIGH QUALITY TECHNOLOGY!
Hope this helps
-floatinhead