Can anyone help fitted capri mk1 tank in my anglia, used old style smiths 2" gauges when tank is empty gauge reads half full. fitted new sender still reads same. rang speedy cables to recalibrate they want up £65 is there any cheaper way of getting the gauge to read right

 

some had a screwdriver slot on the back [adjustable rheostat] if it has tweak it one way or the other u will soon figure it out