I have a Heng Long Sherman, 1/16 th scale, the tracks on that are plastic and have never given problems. Metal tracks cost over 40 pounds for this model. The Firm in Germany called
Imperial-Modelbau.de have lots of spares and accessories, they speak excellent English and are often at British Model Shows, Ask them, I am sure they will help, also they are Stockists for heng Long. Worth a try...