Well, I just tried the following on my laptop and it worked --
Lets say you do condor_history and the largest jobId was 1500.0, so
you want to "reset" the schedd job id counter to give out jobId 1501.0
as the next jobId to avoid duplicates. Do
1. condor_off -schedd and verify the schedd is gone.
2. make a backup copy of file spool/job_queue.log just in case, and
then carefully edit spool/job_queue.log to append just this one line
to the end of the file:
103 0.0 NextClusterNum 1501
3. condor_on -schedd
hope this helps,
Todd