Thanks Pchi2007 but TC Electronics suggested I contact their service centers for a spare part, if it was even possible. So far no one has them as I have called.
You´re right... service center.
I remember they asked me if I needed the pot or just the knob.
I looked at the web and there´s only one center in Spain : http://www.solatecnic.com so I guess that´s where I asked.
I remember it took them like 2/3 days to reply my mail.
There´s an english link. Good luck