I have a long winded version with details of this post on the repair forum. I thought I would post on this forum in search of a TL922 Guru that might hang out here. Specific questions are can I operate, for the purposes of testing, a 922 with just one tube installed. One of the tubes that came with the amp the filament would not light. The issue is when keying the amp with zero drive the Plate current meter pegs “hard”. I’m reluctant to install the new tubes until I know what is causing this.