For future reference, I analyzed the case feeder set up piece by piece to try and determine what part of the system was causing my difficulty. I believe I solved the problem. Underneath the funnel tube is another short piece of tubing with a lip held in place with a clip. This piece of tubing is too short. I removed the clip and elongated the screw hole used to secure the clip to the case feeder shell bin. This allowed the tube to hang lower and not pull out of the middle piece of tubing that holds the sensor.
It now seems to function well, but the question remains why would this modification be needed? I'll be calling Dillon on Monday to discuss.
Why, because everything has tolerances and sometimes they stack against you. Also might depend on how old your machine is. I had a very early 550 and bought the feeder when it first came out years ago. It absolutely would not come close to fitting. I live near Dillon so I took it over and they said "wow, you have one of the original 550s!" 'The frames are different and we have been looking for one to see if the feeder can be made to fit." They gave me a brand new 550 and installed the feeder for me. A couple of weeks later they said they had concluded the really old frames simply would not accept the feeder. If it works don't sweat it.
I ran into the same problem with my older 550, the work horse of the fleet. Now I just have one 550, and two new 750's. The 750 is a great machine. If you like the 550, you will love a 750 with the auto indexing. Loaded 750, 44 Special the day before yesterday. 1500, 45ACP yesterday, and 500, 357sig so far today. I wish you could load shot shells as quickly.
I have to be honest here. I believe the new 750 is one of Dillon's best loaders yet without going to the 1050. I love mine. But I still maintain the 550 for loading stuff like 300BO, 44 special, 308.
Stuff I don't shoot a lot.