On helicopters that use belt driven tails the belt tension should be checked on a regular basis as the belt does tend to stretch. Like most aspects of our hobby there are a lot of opinions on how tight this belt should be. Some maintain that it should be as tight as possible to prevent skipping. Others say having it too tight wears out the components. A good method tighten this belt is as follows: There is usually an inspection hole at the front of the tail boom. You can press the belt with your finger to determine its tightness. Place the helicopter on you workbench or kitchen table and press you finger against the belt. If the belt has the correct tension you should be able to push the belt half way to the other side before the helicopter starts to slide on the table. If you can press the belt until it touches the belt on the other side of the front gear the tension is too loose. If it barley moves before the helicopter start to slide then it is too tight.