You can't fix it if you don't take the top off, it's not a problem to adjust when you put it back together. Snug the bolts down so it doesn't leak put the front on stands and start it up DON'T reach through the steering wheel it could turn and wack your arm if the valve is off center, then take a small hammer and tap the valve assy from front to back and the wheels will turn right and left. When you get it centered tighten it up and shut off the engine start it up and see if the wheel kicks right or left if it does loosen the bolts and slightly tap the valve and retest till the wheel does not kick ether way and your set. I've done it many many times and that's how you do it.
