Pretty simple job to replace the "O" ring. Pull the wheel off, remove two screws, remove the "o" ring and replace. Buying just the "o" ring is the problem as it is part of a seal kit. 50 cent part in a $45 kit. BTW, be sure to get the oil cleaned up off the carpet, it will lift the glue.
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95 Ranger 361XT, 175 Mariner EFI