Flex :: Image - ComboBox Items Go Out Of Alignment

I have a combobox that uses a custom itemrenderer to display an image. when scrolling up and down the list the images randomly go out of alignment. How do I stop this?

public class PinRenderer extends UIComponent implements IDataRenderer, IListItemRenderer {
private var currentPin:DisplayObject;
private var _data:Object;
public function get data():Object {
return _data;
} public function set data( value:Object ):void {
[Code] .....