NO HF arc start on my CT520

My CT520 suddenly lost its HF arc start, I've been scratch starting it on TIG, but this is really shortening the tungsten electrode resharpening time. Any suggestions on how to fix the HF circuit? The manual that came with this unit is useless and almost unreadable. I don't want to start monkeying around inside this unit without some guidance and diagrams. Is there a HF circuit board that can just be replaced?
Thanks Jon C.

Jon,

Did you try the HF adjust instructions here?

If you can PM me your phone number and I can call you and walk you though it.