My Fender DRRi broke up today. I only get low very distorted (fuzz like) sound. Both channels. Checked all the tubes and speaker. Disconnected reverb. I belive power is not getting to power tubes as I checked BIAS and values are very very low. I'll be opening it up to see if I can find something before looking for a tech (hard to find a good one around here). What should I look up to? Caps?