As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW OBSERVED TAKEOFF WARNING HORN AT THE BEGINNING OF THE TAKEOFF ROLL. REJECTED TAKEOFF, FOUND ACTUATOR FOR S867 (SPEED BRAKE WARNING SWITCH) OUT OF ADJUSTMENT. READJUSTED ACTUATOR AND PERFORMED TAKEOFF WARNING. CHECKED GOOD PER MM 31260. NO FURTHER PROBLEMS NOTED. OK FOR CONTINUED SERVICE.