This is part of the procedure explained in post #1.Found this info about the oil filter housing from the engine manual kindly posted earlier:
"The oil filter housing has a service drain facility. When the cap is unscrewed 3-4 turns, a drain hole is opened allowing oil to
drain into the crankcase. This allows the oil filter element to be removed with no oil contamination of the engine or
Might be useful to unscrew it as suggested before starting the drain (or suck) procedure.
Sorry it is not much help if the filter cover is stuck....