Checking steam mains pitch

leaking

12 unit 2 story, 110 ft main run, I have an area that knocks. An area on the end that doesn’t get enough heat. Building has settled from to many trees I planted and hangers may be missing from construction. Pipes have asbestos covered over with fiberglass insulation so removal to see pipe is out of the question. total insulation is about 6” thick . How do you check if the supply and returns have proper pitch back to system ?
First I thought to take a long maybe 6’ piece of straight wood or aluminum. Attach securely two very long nails or sharp metal, one to each end, and attach to the long piece of wood-aluminum a level . Then push the two nails on the end of the 6ft piece through the insulation to the bottom middle of the Main. And read the level.
Second idea is take a decent Laser Level, (I purchased a 50$ Bosch) and attach it to a bracket I make , so it hangs under the pipe . And a second Bracket I make the same , To where I want to read it with a lined paper showing if it is level or pitched. I am guessing on all of this. How do the Pros do this ?

Intplm.

The best thing is to get a good look at the pipes. But since that is out of the question due to the insulation issue you surely can try what you have mentioned above. You can also just eyeball it.

I would replace the missing hangers and adjust the pitch with the hangers. You can use clevis hangers or a tear drop type hanger combined with an insulation shield pictured here. This will take some experimenting on your part till the banging subsides.

I would also look for a valve that might be partially opened or a non-concentric reducing coupling, or another type of fitting that might be causing the build-up of condensate in the line.