Yours is a Hang Long Tank. Your sound system as well as the smoke system are out of order. If you try to fix them, it costs you more than $100 to buy the parts. On the other hand, if you want to upgrade (modify) your tank by replacing it with metal gear box and metal tracks, it takes you another $400. So better think to buy a new upgraded version with metal gear box and tracks.
So many problems, you better use it as a source of spare parts and buy an upgraded verson. In HK, it cost lest than $1000, but if you buy it from China, it is much cheaper