too easy,it may not be the o rings,make sure those brackets that hold the screw for the covers are flat and not twisted or have burrs,flatten and file them accordingly,then throw away the old aluminium washers on the hold down bolt and use a 6mm copper one top and bottom of that bolt,i like these thin ones,i replace any sealing washer with these,you owe me a beer.
this bolt has oil pressure behind it.