[HAM] HELP! chorus on CV

[Karlo Lovrić]

Hello, list!
On my CV console, there is a Boss parametric EQ connected between the rheostat box and input of preamp. Then, the Hammond is connected to Leslie 760 which has a MIG tube preamp installed on it's input.
Today I've experimented something with those units, on my Boss EQ, there is level pot and I turned it too loud.
Something has oscillated in the amp when i turned a volume pedal to loud. Something like feedback in very high tones. Since then, chorus is missing... :(  There is only vibrato when chorus is on. When off, it's straight.. But no mix.
Is a 6J7 tube in the preamp for mixing vib and straight signals?
Is it possible that I've burned this tube? Maybe something else?
Thanks for any info!!
Karlo.