That's the problem, there are at the moment no procedures or procedures so old they should be written in stone. All the warehouse staff have done the job for many yearsa and therefore fell no need for written procedures etc. I'm looking for ideas of areas to look.
Follow your processes from the beginning. Meaning, start at the front door of the organization, walk through all the steps.
1. Receptionist (customer service)
2. Sales
3. Order taking
4. Order entry
5. Human resources
6. Manufacturing
7. Product testing (internal auditing, final testing and so forth)
8. Packaging
9. Shipping
10. Customer follow-up
These are only a few steps (not absolute) that could be used, since I really don't know anything about your organization.