ERROR: file C:\Program Files\sapinst_instdir\ERP\LM\COPY\ORA\EXP\CENTRAL\AS\EXP\REPOSRC.TSK.bck already seems to exist
a previous run may not have been finished cleanly
file C:\Program Files\sapinst_instdir\ERP\LM\COPY\ORA\EXP\CENTRAL\AS\EXP\REPOSRC.TSK possibly corrupted
You just change the name of the file REPOSRC.TSK.bck and REPOSRC.TSK
It works for me.
Good luck.