I had the same thing when i moved here. YOu only need to take out new galls as the old ones have already done the damage. I have a Meyer lemon which is always covered in flowers and fruit, I moved here 9 months ago and this year, after the main cropping season, i gave it a very harsh cutback. IT is now covered in fruit and flowers again and forming new shoots where they should be. I live near Maleny so the soil and rainfall are excellent. I think that really helps. The old galls are easy to spot, as there is lots of new growth after them, and you can see small pinprick holes where the gall wasps have already emerged. Better to get them on the new growth as you see them start.

 Okay thank you very much. I have put up a wasp trap too, so hopefully that will prevent too many new ones