If it is a conventional lip seal and comes out "outwards" - one accepted practice is to drill a couple of small holes (maybe 2mm?) at top and bottom, or at each side - wherever access allows - and screw a pair of short TEK screws into the holes so the heads are maybe 8mm out from the surface of the seal. Then use a baby pry bar or perhaps a claw hammer, or vice grips and a big screwdriver as a lever - and pull them out. Have a google - there will be videos explaining this for sure. Cheers