As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PILOT HAS BEEN COMPLAINING ABOUT THE VSI AND THE ALTIMETER JUMP APPROX 100-200 FEET AND THEN SETTLE DOWN. THIS ONLY HAPPENS DURING A LIGHT RAIN OR HEAVY MIST (NO ICE). WHEN HE TURNS THE ALTERNATE STATIC ON, THE PROBLEM GOES AWAY. THE STATIC PORT HAS BEEN CHANGED, THE STATIC SYSTEM HAS BEEN CHECKED OUT AND ALL ALIGNMENTS HAVE BEEN CHECKED.