Screech when turning tube pre on

Hello folks!

Well, after my issues (Cary AE3/AES) yesterday, I finally managed to get the thing working. A few problems though.

1.Turning preamp on causes sharp screeching and distorted noise. After a few short seconds it goes away and music resumes normally.

3.There is static/hissing sound coming from both channels as well, although the noise is only audible when I put my ears right next to the speaker.

4. Raising the volume slightly increases the hissing noise.

Since the hissing increases as the volume is turned, then the problem exists before the Volume dial.

I believe the problem to be a solder joint in the audio selector since the selector came off during shipping. Any thoughts?