What happens when you try to drop the table?
The first approach I would try is to try to drop the index that has indid 3, and if that drop succeeds, then run a full tablealloc with fix on SETO_corrupt
If that doesn't work, then dropping and rebuilding the full table may be the necessary step. I've been using the "how to drop a corrupt table" script for 20 years without any major problems. The typical issues have been due to new system tables / system table entries that cause the script to need to be updated (these can usually be caught by running dbcc checkcatalog after running the script), and that on very large databases the dbcc extentzaps can take some time to run (they have to process every allocation page in the database).
-bret