Concerning flame roll-out during ignition (Goodman Furnace GMPN100-4 Rev B)

Concerning flame roll-out during ignition (Goodman Furnace GMPN100-4 Rev B)

I'm experiencing flame roll-out during ignition, but not during operation. I think I've identified some sort of leaking air around the middle heat exchanger coil - tested by having the fan on and using a flame test (per https://www.youtube.com/watch?v=WABAnzUthAg). Also, when in AC mode I can feel slight cool air in the area. I've captured videos and pictures.

What are my options/next steps? I'm open to replacing the heat exchanger (it seems like a 4-hour job); however, I wonder if possibly there is a leak where the heat exchanger connects to the panel. When I removed the burners the other day to make sure they were clean, several of the screws surrounding the gas inlet were loose. I tightened them; however, the problem remains.

Input line NG gas pressure: 8.2 in WC (a bit high)
Operating pressure: 3.5 in WC (seems in range)

Panel Info: https://1drv.ms/u/s!ApoIzd-YZYEfheAh6upPYgfHDXCxwQ?e=fv3l33
Input line NG pressure: https://1drv.ms/u/s!ApoIzd-YZYEfheAfcsSg5MzFEP4UIA?e=81eBkd
Starup video (rollout and operating pressure) https://1drv.ms/v/s!ApoIzd-YZYEfheAdyU5RXCR7fhKW-g?e=i83dmq
Operating (image): https://1drv.ms/u/s!ApoIzd-YZYEfheAe3PCrOAgxzXZO4w?e=N8YRPy
Flame test (video): https://1drv.ms/v/s!ApoIzd-YZYEfheAjol9D5w1rF5hRDQ?e=eqJ2wc