Petrol gauge prob

[Bobbit]

My petrol gauge has a mind of it\'s own. Will show as full when it is then will stay then untill about 1/2 full the it just stays there, so i\'m always filling up at 1/2 full as dont want to run out. Recently changed the dash and i\'m 100% sure it\'s not a problem with the connections so i\'m thinking it\'s the sender, is this an easy fix?

Thanks

Rob