I am assuming that the 6A inline is the one blowing. Anyway in general you calculate all of the amp draw on a fuse and size to that number or near. Add up all the watts of the bulbs (available on the internet, using the bulb number) and motors, etc. and divide by 6(V), that will give you the total amps drawn on items that could be energized at the same time thru that fuse. Probably should check the wire size while you have the numbers handy. Technically, fuses should be sized to wire size. They are really for fire protection but we assume they are to protect devices, which they do. But it's all related anyway.
