Deep Countersink
Double Seam Components - Cause & Remedy

The Countersink measurement should be approximately equal to the thickness of the Seaming Chuck flange to a maximum of approximately .005 of an inch greater than the thickness of the Seaming Chuck flange.

Deep Countersink 
Probable Cause Suggested Remedy
Excessive clearance of 1st operation seaming roll above the seaming chuck Reset 1st Operation Seaming Roll height to within a maximum of .003 of an inch over the Seaming Chuck flange when it is at its furthest inward travel. A lesser amount is desirable providing that the Seaming Roll doesn't drag on the Seaming Chuck during its operation
Diameter of the Seaming Chuck greater than covers used Replace the Seaming Chucks
Seaming Chuck flange thickness is too great. Replace the Seaming Chucks with the proper thickness
Worn 1st Operation Seaming Roll Replace the 1st Operations Seaming Rolls. See Parts List Instructions or Service Manual for this procedure.