Problem with top burner on Blichmann Top Tier Stand

I have a Blichmann Top Tier stand with three burners. I have it set up with three different tiers. My HLT is the highest of the three tiers. I can get a good, efficient blue flame with my BK burner (lowest tier) and my MT burner (middle tier), but I can never get a good flame on the highest tier.

Has anyone else experience this before? The top tier has the longest run of gas pipe in the manifold, so I'm wondering if that is part of the problem? I'm really not sure how to troubleshoot and would prefer not to take tier and manifold apart if there is another way to determine poor performance from one of the burners.

Does it work with no other burners running? It sounds like there might be a restriction in the fuel line or possibly an obstruction in the fuel/air mixture tube on the burner.

Check your burner for spiders or other debris.