I have a 1990 Carver PT1250 that I've run in stereo for years biamping 1820 ccab, sending highs to the 10's, lows to the 18's. I recently ordered a Schroeder 410 to replace my 1820's I now want to run this amp in mono. The owner's manual says: "internal jumpers must be moved before mono operating mode is allowed. These changes must be made at the factory, or by a qualified service technician." Carver does not answer their customer service phone:360.862.1742. I've left voice mail... Can any of you hotshots walk me thru this, or guide me to some one who can? Please?