So here is my suggestion. I would try the straw/spray tin of brake cleaner or contact cleaner into the nozzle. Then I would rig up a container of oil to immerse the oil sump. I would then run the oil pump with a drill and see if oil comes out the nozzle. I think this may be possible. To get at the back of the plate you would probably have to remove the crank timing gear. The three flathead screws will have been staked in place with a punch. You should dress those first. Then use an impact/hammer drive to break them loose.
