My rc heli wont go up - xheli 3 Channel Alloy Falcon Aluminum RC Electric Helicopter RTF w Flashing LED

Hi, everyone.
Ever since I saw the first advertisements on YouTube, some years ago, I wanted to acquire one of these little helis. When I finally acquired one, I had lots of fun until the little thing started to give me trouble.I own several of these mini-copters and have managed to maintan most of them in good working conditions for about 4 years now.
I would like to share some things that I have learned about RC Infrared Helis, specifically speaking, the airhogs RC helicopters.
First of all these little copters are not intended to be used outside home unless on a very calm day and on an area that has to be protected against sunlight, because sunrays interfere enormously with the IR beam with which the Infra-red light-emmiting controller communicates with the copter. I have found out that even while flying an air hogs copter indoors, when you get them close to a ray of sun shinning through a window, it suddenly drops to the ground.
Next, Most problems that I have encountered have to do with a combination of low battery power, plus trimming. In some of these copters, trimming can take a great deal of pulses before you can get them to fly right.
On the first models I would cut a cardboard fin and tape it to the front of the heli, below the nose and across form it, side to side to make it thrust forward.
Many times there were things like hairs or pieces of cobwebs attached to the axle of the back rotor, causing the heli to spin uncontrollably, even after trying to trimming it with the remote contol.
On other ocassions the copter wouldn't hold a charge even with fresh batteries on the controller. I learned that in time, the charger connector/plug may get dirty, so I usually spray the inner part of these connectors with a light coat of contact cleaner(available at any electronics store like Radio Shack) and then plug and unplug the connector a few times. This has worked fine with my older copters that have presented such problems.