WHEW .... at least it was 'outside' and EASY to fix !! BTDT ( screw had magically 'disappeared' )
If the gasket is the one between the axle and the steering hub part, you'll need GOOD 'medium ' sized snap ring pliers, 'bent' ones work best. There's a snap ring that has to come off. online parts has a good diagram of what goes where. magically the left side stopped dripping, now the right one drips. TOO dang cold to work here...maybe in 55 days when Spring arrives.
You can download the WSM, kinda explains the process, i think, been 5 years