My rc98hp manual says for cleaning: remove front cover and blow fan blades and heat exchanger,etc, clean. well the fan is at the back, and looks like major dismantling to remove to clean. Is that what I do or am I not catching on? Is there a more detailed (repair) manual available? My older Rinnai is very simple to service.( the outside screen is too big and flies get onto the heat exchanger grid). Fan removes easily, etc. Please help me! Thanks.