GE side by side fridge, fresh food side not cooling enough

Ge side by side fridge model GSC23LSRDSS. Fridge side is a little warm, about 45 degrees at cool setting 5. Cranked up to max cool (9) it barely gets to 40. Evap coils lightly frosted all over. I had found the evap fan was not moving. I replaced the fan and the circuit board. Still having problem with fridge not quite cold enough based on refrigerator thermometer. I removed the damper and it appeared to be wide open when completely removed and unplugged. It flopped about 1/4″ when shaken, and looked like it might be hitting the corner of the fan. That fan works, by the way. I was unable to get it in any position other than just about wide open by shaking it. It seems like it ought to be too cold, not too warm! I put it back together and I’m stumped. My customer already paid for a new evap fan and circuit board and I’m not confident that replacing the damper will help, even though it may be broken. What else might cause this?

Setting the fridge at cool level 5 brings it to about 44 degrees. At 7 it gets to about 42, and it barely gets to 40 when set all the way to 9 (max cool). The freezer will get down to -9 at max cool. No defrost issues that I can see. Nothing blocking the air flow into the fridge.