I've just received 72 ft of Accucraft brass flex track and I must be missing something.....how is the track coupled together?? It came with a handfull of brass slide on couplers(I guess that is what they are for), however they do not fit tight. Of course no suggestion was included. What more do I need? I have a four year great granddaughter who loves trains and I've finally got a place to run two tracks over a straight run of 40ft. Also building a 12ft x 12ft for a round or oval track layout....Thanks in advance. Charles Rakes