As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FT # 421, JFK-NAS. DIVERTED TO PBI, EMERGENCY DECLARED. AT CRUISE EXPERIENCED BURNING SMELL IN CKPT SMELL GRADUALLY WORSENED FOLLOWED BY VISIBLE SMOKE. SMOKE & FUMES WERE ISOLATED TO COCKPIT ONLY. CAPT ELECTRIC SEAT ADJUSTMENT STOPPED WORKING; ACCOMPLISHED TSM 05-50-00-810-831-A ISOLATED ODOR CAUSE TO CAPT SEAT ADJ MOTOR VERIFIED TO CAPT SEAT C/B TRIP R/R CAPT SEAT IAW MM 25-11-51. OPS CH NORM.