1992 Toyota Camry No Heat

Hi Guys,
I just purshased a winter commuter (92 Toyota, Camry) Problem is now that it's gotten colder I've discovered I do not have good heat. The radiator has fluid and I believe the T-stat is working because as often as it is driven the temp gauge always stays in the normal range. I checked the heater controll valve and the lever/arm makes it's full movement when selecting Hot or Cold. Finally feeling by touch the hoses that run to the control valve and the short 3 inch one that continues to the intake port of the heater core all get hot / feeling normal. The hose that exits the heater core is cool. Does this mean that the heater core is the problem then? Can a coolant flush with cleaner help or will a replacement be most likely? And if it does need changed out - what is the level of difficulty on this particular vehicle/model.92 Toyota Camry, Auto, I4 2200

~bri