What's wrong next to my hot river electric fire? About two weeks ago my hot water suddenly seem to lose pressure....

About two weeks ago my hot water suddenly seem to lose pressure. The cold water pressure is commonplace but the hot water pressure have dropped to about 1/4 of what it be. I've checked the best that a can and it would seem that the pressure of the cold marine going into the water radiator is fine but the pressure of the water coming out is low. I've flushed the reservoir out thoroughly hoping that was the problems beside no success. What else could be cause this?
Answers:    is the temp p/r valve leak???/ Is the tank leak??? Is the outlet valve fully open????? remove the outlet pipe and see if it is gunked up>
could be any number of things, but probably is gunk in the outlets or at the spout.