prr1361...welcome to the club. I'm running similar (American Flyer) postwar trains, and I'm also a novice. My first suggestion, though, is to do some internet research---there is a wealth of information on sites like this one, and on sites that sell parts. It's their business to make you feel confident to repair your own, so let them teach you. I'd start here:
http://www.hobbysurplus.com/americanflyerlocodiagrams.asp#steam type info
Drop down the blue column on the left and follow Lionel.
Heat (the guys on this site teach you everything!) either suggests an electrical problem or a need for cleaning and lubrication; I'd start with the clean-and-lube. Your stuff is similar technology to mine; if I can figure it out, it can't be very complicated. Open her up and carefully clean the dust out with a soft toothbrush, q-tips, soft paintbrush....get all the garbage out. Places of electrical contact can be gently cleaned with a pencil eraser to get the carbon out and improve the connections. Gears get grease: everyone here seems to agree on the white lithium stuff you can find in small tubes at Walmart. There are separate opinions on oil---I use 3-in-1 sewing machine oil. Guideline is that gears get grease, bearing surfaces get oil. Don't flood it---just lube it. Oil the rolling surfaces on your axles.
If you open the engine up to get at your armature, be careful not to drop the brushes and springs. In my trains, the brushes are metal cylinders with springs behind them, mounted in brass tubes under the engine cab (wiring runs to them). They fall out and roll away, so you might want to work over a sheet pan. Also, use the rubber eraser on the metal wheels that pick up your current---you may need something coarser, but I'd start with the eraser. Best of luck, and show off your work with some pics on this site!