As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE RADAR HAS BEGUN TO SHOW SPIKES ON THE DISPLAY IN MANUAL MODE. SPIKES ARE INTERMITTENT AND VARY IN INTENSITY FROM MINIMAL TO QUITE DENSE. GROUNDED - YES. REMOVED AND REPLACED WEATHER R/T, TESTED NML REF AMM 34-43-41-00-801 & -400-801. ALSO OPERATED RADAR ON GROUND IN MAN MODE - DISPLAY HAD NO SPIKES.