TubeNet

I have little knowledge on how to adjust rotary valves. Is this a use a borescope or mirror like piston valves or do you look at the marks on the back of the valves under the bottom cap and make them line up? (Maybe the best thing is to just take it to my tech.)

Using the lines on the rear bearing plate and rotor axle usually works fine provided that the rear bearing plate is properly aligned to the rotor housing AND the horn is a brand that is known for good workmanship such as Miraphone Meinl, B & S, or other European brands. That being said... I still like to verify alignment with a borescope or direct vision if the rotor is off the horn.

I've seen MANY brands of lesser quality where the marks are off or missing altogether.