@wyldepaws Just to add, when I got my current basenji he was a return. The prior owner said he was aggressive lol, nothing could be further from the truth.
However looking back he did have some problems, he doesn’t like loud noises although that has become better with time. He was nine months when I got him and is six years old now. It took time with the nail clipping as he would panic and struggle. I lay him on his back in a chair on my left side / lap. Then I do them with a Dremmel on low speed, he doesn’t like it but he doesn’t freak out. When he gets agitated, which is usually the third paw, I take a break and talk to him calmly / soothing, but I don’t let him go. He also knows a special food reward is coming after they are done. In fact he licks my face sometimes which distracts him lol. We have got to the stage where he doesn’t like it but it’s not a big deal anymore.
When he freaked about a loud noise I would ignore it and try to distract him. Also I would speak in a curious voice or happy voice to him and laugh, which helped. It’s counter intuitive I know but it lets him know that I am not worried about things. The less I reacted and made it no big deal, the more tolerant he became to noise.
A really good way to gauge the fear is the eyes and ears. If he is very fearful his pupils will be dilated and be huge, the ears will be back or down.
It is good that he reacts by running away, some dogs react with aggression and that is far harder to deal with.