DC16 will run for about one minute. Switch on again and will run for 3 - 4 seconds. Machine is clean. No corrosion on battery. Battery is reading 22 volts. If I put my finger over the nozzle to restrict airflow when started there seems to be good suction for about 2 minutes, then it stops. Switch on again and it will only run for about 3 - 4 seconds. After a few minutes it will run for about a minute when started normally.