oil filter

New member carrying out some refurb maint on a low mileage zzr600 E8 (2000). Really struggling to understand how to get oil filter out of the confines of oil cooler and exhaust manifold pipes. Reading the manuals suggests it should come out through the pipes once the oil cooler has been dropped...

To avoid paying Kawasaki's prices for O-rings, anyone know the sizes of the O-rings in the oil pan area (feedpipes, filter screen and filterhousing) please? Particularly the o-ring/seal thats flat on one side Also are they buna-n or viton? Cheers