Midrange breakup

[sdorer]

Friends,
I completed a build od a 5E4 circuit, which is a 5E3 with a cathode follower rreceding the tone stack. Regardless it sounds wonderful but for intermittent break up in the midrange notes of the guitar which is exacerbated by increasing the volume. The break uo sounds like a crackle/static along side the note not distortion. Any ideas about what I should check. Voltages on the various circuit sections are fine. One other thing, stroking the chassis with a finger can cause noise intermittently , meaning sometimes it causes noise and sometimes it doesn't. Is my ground scheme faulty? Any insights would be appreciated.

[Structo]

Can you post the schematic you used?

Do you have a three prong power cord with a chassis earth ground?

[VacuumVoodoo]

I would suspect a bad solder joint or even a joint you missed to solder.

[sdorer]

I will check the connections. Here is a schematic.