I am about to give this up! I dont know what to to any more.. Please Help me!

Is there anyone how have seen this beakproblems before??
I have been to the bird-vet here, and i beg him to take som test to se what this really is and how to treat it, but i just got the answer; he had never seen this before and they cant take any test to se what this is, and then he give me som Ivermercin ( i TOLD him i allready have tried both scatt and S76, but he didnt care ), so i go home, frustrated, with more ivermercin and a bill for 80 dollars ( for what?? )

First it was on one bird, now... well.. i have 4 ( in another room ) how hasent got it.. I have tried scatt and s76, both direct on the beak and as usual for the ASM-threat, no reaction. I have also tried to take som paraffin-oil on the beak, and its a little bit of help, but its seems to come from inside, because its never dissapears totally.
The birds are healty and happy, exept for this enoying problem!



I dont know for how long the first one have this problem, but its over a year i believe, the others got the first signs about 7-4 months ago.
You are my last hope, please help..

( Sorry for my bad English as usual.. )