If you are using an 8 cell 2/3 A battery pack try the new GP 1100 mah or the CBP 1050's these have higher output and longer duration than the Kan 1050's and the 1050's are only $1.35 each The CBP 1050 8 cell pack is about $17 and the 1100's about $25.
The CBP batteries in my opnion are far better batteries than the Kan's. I have had a few of each.
Try these guys for excellent prices and selection
http://www.unipros.com
Wood Duck