Also what is the easiest way to lube it? to i have to take it apart to do it?

I just bought a 608 4-8-4 class J and it sounds like it has a chugging sound coming from the inside of the engine and also at low speeds it kinda jerks, and before you ask, no it doesnt have a sound system in it lol. its the DCC ready 608 freight version. Any suggestions?