DIAGNOSIS The motor thermal overload protector is tripping. Cause is either a failing motor or blocked cooling vents.
FIX Unplug it and let it cool completely. Flip it over. Inspect the intake vents on the bottom and the exhaust grilles on the sides. Use a vacuum with a brush attachment to remove all dust and debris. This is the most common fix.
IF THAT DIDN'T WORK The motor brushes may be worn out or the armature is failing. This requires professional service. Contact Vitamix. The 5200 has a non-user-serviceable motor assembly.
HEADS UP The thermal protector can fail permanently if tripped repeatedly. If cleaning the vents doesn't solve it, stop using it to prevent a total motor burnout.