As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA FLIGHT NR 2064, UPON TAXI OUT, AIRCRAFT BEGAN TO SHAKE, WHEN APPLYING BRAKES SHAKING GOT WORSE. REPLACED ALL 4 BRAKES IAW T/C 93424201. TOK AIRCRAFT OUT FR TAXI, NO VIBRATION NOTICED. OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.