Need some help from you amp gurus. Got my new power tubes installed but I want to check/adjust bias. I'm thinking since the original tubes were still in there that this hasn't been done for over two decades. I know this can be a dangerous thing so I will definitely observe the one hand in pocket rule. But I have to know how to do this! I've attached pictures and a schematic for reference. From what I've read, I need to check between R39 and R40. But where the hell is the trim pot? I was in there at the end if a long day so forgive me if it should be obvious. Any help will be appreciated! This isn't about saving the $30 on having a tech do it, I want to learn! Thanks guys!