Sunn Beta Preamp - no output on pin 7 of the first IC 4558

[Mardn]

hey there,
i'm still struggling with the sunn beta preamp as there's no output on pin 7 of ic2 (see pictures below).
i got almost 15V as powersupply --> 14.6V...should work

i did continuity check on all the wiring and solder spots on the board and also checked for shortcuts with no negative result. i checked the parts and spots where they have to be placed a million times now and couldn't find any mistakes so far.

i traced the audiopath with an audioprobe and found that the signal get's lost on pin7 of ic2, which should be output nr 2 of the first 4558 ic. i tried several LM4558DD JRC and RC4558P with no change. i then checked for a shortcut connection to grnd or -15v...nope.
i'm getting input on the inverted opamp on pin6 but on out2 it's gone.

in the following you get some pictures of the build as well as the voltage mesurements.

it'd be great if you guys could give me a hint, where else to look. i really would like to get this thing working.

thanks and cheers, martin