Antenna issues after swapping motherboards

Hey all! I swapped the motherboard of a i9305 to a i9300 since they are identical in almost every way and needed a new screen. However now when I turn it on it has zero or one bars where it once had full bars in the same location.

If anyone has any suggestions they would be very much appreciated. PS I already tried replacing the signal cable/ antenna from the i9305.


Thanks!