Are your Corbin Russwin ED6200 key cylinder and Thumb Piece not working?   If so the cams and levers in the Corbin Russwin Active Case Sub Assembly 397F99 are probably worn, stripped or just plain shot!  The Corbin Russwin Active Case Sub Assembly includes are all of the cams and levers, along with the latch bolt, latch bolt springs and slide.   The cams, levers and slide lock and unlock the exit device when the key is used.  This Active Case Sub Assembly is uned on the Corbin Russwin ED6200, the Corbin 3729 and the Russwin 736.  The Sub Assembly is our part # G37240, and is readily available.  If you have questions on this product or any other door product we sell, please call or email and speak to our exit device and panic device experts.

the above image is of the Corbin Russwin ED6200 Active Case Sub Assembly

The Corbin Russwin ED6200, 736 or 3700 latch bolt not extending is usually caused by one of two problems.  One of the problems is the crossbar screws, tenion sub assy, and crossbar are not tight.  The Corbin Russwin ED6200, 736 or 3700 does not have a heavy spring on the active side case, it is on the inactive side, and if it is not tight the crossbar will move from a non parallel position to the door.  This can be corrected by tightening the crossbar screws, but sometimes you have to shim the tenion sub assembly.   The only problem might be the springs or the active housing.   I would try the Crossbar screws first.