Filament Tracer- Not picking

Hi,

I have a sample of bacteriophage. I want to solve the tail. The diameter of the tail is around 300 Ang. I am not able to trace it. I have tried both template and template free options. Kindly suggest. How do I effectively calculate the Separation distance between segments (diameters) and Minimum filament length to consider (diameters)? I have shared the screenshots of the template (187 particles) based tracing.