I'll check that out. Company rep told us to run in full up position but I have little faith in there opinions. After all when was the last time a company guy ran a machine with millions of his own money at stake?
Checked slats on feeder chain, and inspected inside of feeder for signs of contact...negative.
Concluded that it must be uneven feeding causing feeder drum arms to contact upper and lower stops abruptly. Made some changes to setup of 2020 head waiting for weather to break to try again.