This hole is a pressure relief valve. The valve is designed to release steam if something is blocking the steam path inside the unit. (**CAUTION: This area may be hot**)
- Unplug the machine and check for clogs at the spray tip with mop head removed by taking off the single screw at the base of the unit. (**CAUTION: The spray tip may be hot***).
- Clear any clogs from the spray tip by inserting a paperclip into the spray tip opening.
- Check the filter for cracks. If the filter is blue in color (or has a solid rather than speckled appearance) it should be replaced. A replacement filter can be ordered from BISSELL Consumer Services either online or by calling 1-800-263-2535 Monday through Friday from 8 A.M. to 10 P.M. or Saturdays from 9 A.M. to 8 P.M. ET.