Do you experience problems during downloading?
Check your connection in Status and Interface settings window.
Use Test Server in Config > Servers.
We will probably ask you to do a test using only basic settings.
Do you experience problems during repair or unpacking?
Enable +Debug logging in the Status and Interface settings window and share the relevant parts of the log here using [ code ] sections.
Using smpl, just clicking the button in config->general is enough. No need to even save the changes. A new nzb key appears in the form field, and as of that moment, the log is spammed with: