504 Tarm boiler

Hi,
I just saw one of these the other day in a freind's basement. He is renting the house. The boiler is a 1978, looks really clean, and has the yearly cleaning/inspection done. I have never seen a multi-fuel before this. There is also about 4 tons of nut in the basement that he can use. My freind is not a coal burner but may become one soon....now. I am a hand fed stove burner so I know the basics. I was looking at the coal side of the boiler and two questions come to mind. Looking at the coal grates, just above them on the left side of the firebox, there is an opening that goes into the middle area where the chimney is located. How can you build a deep bed of coal with that opening there? Is there a plate to cover that while burning coal? I read about the damper and it's four positions that is inside near the chimney area. I understand that part.
The baro looks like a simple, non-adjustable one you find on an oil burner, should that be switched to a RC model? Also, there is a cap for the baro... chained to it. On the cover, ingraved in the metal, it says to install the cover when burning solid fuel, but I think they mean when burning wood.
Thanks, Glynn

Thanks,
I didn't know two grates had to come out and a couple of plates installed. The boiler has coal grates but the entire solid fuel burning area is coal grates. I will have to look for the plates when I go over to his house. The boiler is the same model on the popular mechanic magazine link posted above. I'm not sure of the actual model (It is 140,000btu...DTK50?) . The boiler has the sampson draft controller too and the automatic mixing valve set up. The opening I was referring to is about 4" above the grates, on the left side of the firebox(The fire box is on the right side). The opening goes from the fire box into the center area where the stack enters the boiler but down in the bottom of that area. I know pictures will help a lot and I will get some as soon as I can. I'm just trying to save the guy some money and learn something along the way.
Glynn

I now see that on the left side of the grates where the coal fire box opens into the center area, there an incline that will keep the coal where it belongs. There are 5 grates in the fire box. The boiler is set up for summer running on oil only right now. Other then moving the plate in the middle chamber from horizonal to the #2 or #3 position, is there anything else I need to install or move to begin burning coal?

Does this plate have a purpose?

Thanks for the info!
The boiler has not been used for coal in a while and I burn a hand fired so I'm not too sure how to work this boiler. It is serviced every year but who knows how much the service tech knows about the coal side of things. I should be able light it up like a hand fired. I understand how to adjust the sampson draft control initially and the rest is fine tuning...correct? Is there anything I need to do regarding the oil side of things....to switch it to coal just move the chimney plate from horizonal to postion 2?

Glynn