Just received the HO DCC Ready Bachmann American 4-4-0 Santa Fe - how does one open up the tender - folks at SoundTraxx recommended a decoder (Tsunami 2) with a cube speaker for installation into the tender.  The Bachmann schematic isn't that helpful (I'm a Newbie) pointing at what needs to be unscrewed, etc., to access the inners where the 8 pin connector is that I will have to remove.  Help!

I am set to purchase the Bachmann 4-4-0 American Steam Locomotive - Santa Fe #91, HO Scale and was hoping for decoder and speaker recommendation that would fit into this loco and comes with a plug for the 8 pin decoder - I do not want to have to solder any connections...help!