I’ve never had to drill them – I simply take a construction screw and tap it into the seal casing with a hammer. The sharp tip of the screw has no problem puncturing the casing. Go slow – you don’t want to bash the screw tip into the bearing below. Once the screw tip is through the casing, twist it in to bit the casing and pull the seal out. I grab the head of the screw with a pair of pliers and pry across the top the crankshaft (with flywheel nut in place to protect threads). Usually doesn’t take much effort to yank the seal out…
.
