Norcold 2.7 cubic ft. 3 way fridge wont stay lit on propane

I have the same fridge and the same issue. I do think it is a problem with the Thermo Coupler and like you I see that the fridge probably needs to be pulled to replace it correctly. I have found that if I just push the primer and hit the ignitor then release the primer once the piro-meter shows lit it goes out right away. However, if I keep the primer held for 3-5 minutes it will stay lit and work properly staying lit until I turn it off.