Hi all, The Switalski family furnace is out

Furnace diagnostic. On arrival, the customer said the system just cut out. I found the rollout switch had tripped and needed to be reset. Once reset, the system came on. I checked CO exhaust and found it at 700 ppm. I made sure screws were tight and checked gas pressure, 3.5" wc. The CO dropped to 550, so I disabled the furnace by shutting off the gas valve and unplugging it. Got all my measurements and photos and quoted the customer $4200 for a Trane S8X2B060M 80% furnace.