Polk Monitor 7 Series 2 Audio quality question

Hi, I recently bought a set of Polk Monitor 7 series 2. The sound is generally excellent but the lower mid-range is kind of muddy. Cello, bari-sax, trombone, etc.
Highs and lows and upper mid-range are more crisp and clear. I’m thinking about
new caps or other upgrades. I’m asking
the Forum if this is just the way it is with
this model and very common- or if this is a sign of aging components and could benefit from a refresh? Thanks!