CAL still has several (4) authorized service centers. Two are in the Chicago area. I just had a CAL CL-10 serviced through a local dealer where I purchased it. It took a while, but they got it repaired -- at no cost -- even though the warranty expired several years ago.
Approved Audio Service
583 Bantam Rd.
Bantam, CT 06750
860-567-5801
Electronic Engineers
2522 W. Armitage Ave.
Chicago, IL 60647
773-227-2600
Just Service Inc
2940 N. Clark St
Chicago, IL 60657
773-871-7171
Service for CL2500
Scott Morris Enterprises
1130 Hilfiker Drive
Arcata, CA 95521
707-825-6808
Scottmorris@cox.net