Yup - I also recently saw Corey on Barney Miller as an Amish man.
He also did another Barney as an elderly ex-con who commits a crime because he can't cope with the outside world.
Outside of James Gregory, William Windom and Corey, I am hard pressed to remember another TOS actor who appeared on Barney. Barney Miller had its own little roster of bit players who they used about once or twice a year each as various perps/victims. People like Candy Azzara, Phil Leeds , and especially Ken Tigar, who played a nut who thought he was a werewolf - and then later was possessed, and another who thought he was Christ.
Barney's in our dinnertime rotation of half hour shows to watch while eating. We watch one whole disk, one ep a night, then rotate to another show. It's a couple of months between Barney Miller disks, but even at that my wife and I find ourselves saying saying "HIM again!" (or her) all the time.