Thanks guys...I really appreciate the info.

Just bought a UP 2-6-2 Prairie & Tender in N scale, Product Code: 51551.  Started up like a champ in both forward and reverse.    I was wondering if the headlight is supposed to be operational?  The reason I'm asking is the troubleshooting language had something like, "If the train isn't running but the headlight lights up, then do the following..."  So then I thought, hey, maybe the headlight is supposed to light up on this thing?  But, yeah, seems like it doesn't light up and is only there for decoration.  The schematic doesn't have any wires leading to the light either.  But I just wanted to confirm bc my kids were wondering, "Dad, where's the light?"  Oh, also, how do you change the knuckle couplers to the rapido couplers that came with it?  Thanks!