I' m no expert, but it seems the only thing not mentioned was that your center shot could be off. I had similiar tuning issues with my Magnatec, fairly decent shooting but arrows with poor attitude at the target. I could not meet the tuning rules and make it shoot well, especially the rule of lining up the string, pin and arrow. I took it to three shops before the third caught it. There are two kinds of tools to check this, make sure they use both. I had to send it back to Hoyt and they replaced the risers for free, it shoots great now.

Hope this helps