Update: I followed Bushveld's advice and sent the gun to Gunter Pfrommer. He was able to get the forend off and found that the loop had come loose from the barrel, which he resoldered. Ejectors are now working, too. Turn around was fast and the cost was modest, especially considering that the gun had first been lost and damaged by USPS, which Gunter also repaired. I was very happy with his work and his communication.