I finally had time to do something with my crack. The good news: the static is gone, totally. I replaced the 12AU7 with Philips ECC82 and no more static. But one problem still exists: even with the old tube, i get this loud "snap"- sound in LEFT channel when the device warms up (the static was in right), and after that the left channel is gone. When the device cools, the left comes back again. Seems like heat issue, but where should i start to look?
And thanks in advance, again