Defendant was entitled to new sentence hearing on his conviction on drug conspiracy charges where record showed that Dist. Ct. failed to adequately consider defendant’s primary argument that his history of mental health problems warranted below-guidelines sentence. Defendant presented expert testimony regarding his decreased likelihood to re-offend upon his release from prison, and Dist. Ct.’s fleeting reference to defendant’s “mental health issues” made it impossible to review whether Dist. Ct. adequately considered defendant’s argument.