Greetings, and thanks for the question. My apologies for the delay, I just got in for the evening and saw your post.
I'm sorry to hear about Sammy's ongoing parasite problem. What you are describing is, unfortunately, a concern that we are seeing more and more of due to the parasites developing a resistance against many of the common dewormers that have worked so well for years. Unfortunately, "Safegard", which contains the active ingredient Fenbendazole, is one of the least effective these days due to resistance. We are also seeing more and more resistance against Ivermectin, which at one time had full efficacy.
One of the dewormers that has recently worked well for me is a product called "Valbazen", when all others seem to have failed. I would recommend that you consider discussing this change in treatment with your Vet, as another treatment that may help to get rid if the problem entirely.
It is also very important to repeat the treatment ten days after the initial treatment, as the dewormer doesn't kill the eggs, only the adults. Then, as the eggs hatch, the hatchlings are killed before they reach maturity (ten days later) and the ability to lay more eggs.
One other question, however. Did your Vet say what type of eggs were present? Not all dewormers will be effective against all of the types of the internal parasites that are found among goats. One very common goat parasite is a species called "Coccidia" which requires a totally different type of medication.
Also, it would be a good idea to have your vet recheck the fecal sample to be sure that progress is (or isn't) being made.
I do hope that I've been of some help to you, and please let me know if you have any further questions.
All the best to you and Sammy, and I hope he is doing well soon!