export TSM server 4.1.4.1 fails

Hello TSM experts,

I've got a TSM server 4.1.4.1 running on Windows NT SP6a. In the weekend a full 
export is taken with the command:

export server filedata=backupactive devclass=DLTCLASS1 scratch=no 
volumenames=000375,000383,000009

This has been running fine for quiet a period (a few years), but now the export 
fails with following messages in the activity log:

07/26/2003 05:18:11   ANR9999D xibf.c(664): Return code 87 encountered in
                       writing object 0.9041218 to export stream.
07/26/2003 05:18:11   ANR0661E EXPORT SERVER: Internal error encountered in
                       accessing data storage.
07/26/2003 05:18:24   ANR0794E EXPORT SERVER: Processing terminated abnormally -
                       error accessing data storage.
07/26/2003 05:18:24   ANR0620I EXPORT SERVER: Copied 9 domain(s).
07/26/2003 05:18:24   ANR0621I EXPORT SERVER: Copied 18 policy sets.
07/26/2003 05:18:24   ANR0622I EXPORT SERVER: Copied 60 management classes.
07/26/2003 05:18:24   ANR0623I EXPORT SERVER: Copied 64 copy groups.
07/26/2003 05:18:24   ANR0624I EXPORT SERVER: Copied 110 schedules.
07/26/2003 05:18:24   ANR0625I EXPORT SERVER: Copied 14 administrators.
07/26/2003 05:18:24   ANR0626I EXPORT SERVER: Copied 28 node definitions.
07/26/2003 05:18:24   ANR0627I EXPORT SERVER: Copied 85 file space 0 archive
                       files, 344120 backup files, and 0 space managed files.
07/26/2003 05:18:24   ANR0656W EXPORT SERVER: Skipped 0 archive files, 1 backup
                       files, and 0 space managed files.
07/26/2003 05:18:24   ANR0630I EXPORT SERVER: Copied 27726403 kilobytes of data.
07/26/2003 05:18:24   ANR0611I EXPORT SERVER started by ADMIN as process 76 has
                       ended.
07/26/2003 05:18:24   ANR0986I Process 76 for EXPORT SERVER running in the
                       BACKGROUND processed 344508 items for a total of
                       28,391,836,844 bytes with a completion state of FAILURE
                       at 05:18:24.

Does anybody have an idea what is going wrong here? What is the mentioned 
return code 87? Is this a known APAR fixed in a later release of TSM (the 
client didn't want an upgrade yet).

Thanks for any hints, guidelines how to solve this problem!

regards,

Kurt Beyers