Just spent most of the morning trying to remove the sludge trap screws, the advice to drill 5/16" dia hole thro and hammer in cut off allen key did not work for me, only had 1/4 drive socket attachment x 5/16", so I stepped hole upto 3/8" dia and used 3/8" allen key, and used 1/2" drive socket attachment x 3/8". Screws now removed to reveal solid sludge, whole crank now in soak - For me sludge trap removal is a must during strip down.