My oscilloscope has a diagnostic error+ M1111+ M1112+ M1121+ and M1122. What does this indicate?

My oscilloscope has a diagnostic error+ M1111+ M1112+ M1121+ and M1122. What does this indicate?

These diagnostic error codes indicate a problem with EPROM, U610.This device is either not in its correct socket or its checksum is incorrect.

Due to the age of these products, replacement parts are no longer available. Repairs on these products are available from Tektronix Service on a best effort basis.