What type of pad are you using? The SteamBoost has pads made to fit this machine. If you use alternative pads, it’s very likely they won’t fit properly. Check your nearest Retailer or Grocery Store for pad refills labeled Swiffer BISSELL Steamboost.
If you are using SteamBoost pads and they aren’t fitting properly, check to see if the pad is pushed down in all four corners securely. If the pad is secure, there is no damage to any of the four inlets, you’ll need to contact a Swiffer Pad Specialist at 800-611-2583. (Monday – Friday 9 – 6 EST) or visit www.swiffer.com. Or click on this link that will direct you to the Swiffer Email site to ask a specialist your question: https://pgconsumersupport.secure.force.com/ContactUs?brand=Swiffer&country=United+States+of+America&language=English-US