The section of Hunter’s website devoted to ownership and care makes no mention of fixing broken buckles. However, their buckles are essentially the same as many others. This type is known as a tang buckle, according to Picky Guide. They are also referred to as tongue buckles. Hunter buckles are usually riveted into place on rubber straps. Mending rubber is tricky, as is repairing rivet work. Fixing a broken buckle on a Hunter rain boot is therefore likely to be a compromise.
Straighten the tang with pliers if it is bent. Follow the advice of Derrell Legrear and replace a broken tang with a piece of coat hanger. Cut the wire to size and shape it with the nose of the pliers. Bend the end and squeeze it onto the pin to make a tight connection.
Insert the closed jaws of the pliers into the loop or frame of the buckle, if it has become deformed. Open the pliers, so the back of the jaws press against the metal and reshape it. Continue this process as required to get the loop or frame back to normal.
Remove the buckle completely if it is hanging off and broken beyond repair. As of April 2013, Hunter does not sell replacement buckles. Replace the broken buckle with a new buckle of choice. Glue down the retaining flaps over the pin. Replace the buckle on the other boot to maintain a matching look.
Dab rubber glue between the edges of any tears in the strap. Wipe off the excess glue. Wrap tape around the area and allow the glue to cure. Remove the tape carefully so as not to reopen the tear.
Squeeze loose rivets between the jaws of riveting pliers. You may be able to secure them again. Replace any lost rivets.