Writing a production instruction manual guide

Answer
I can only give you general guidelines. I recommend gathering a team and start with drawing a flowchart of your production process. Then take advantage of the collective knowledge and start determining what can go wrong with your process. Yes, use the risk-based approach and determine what can go wrong with your process that can affect:
The safety of your people;
The quality of your products;
The cost of your production;
The planning of your production.
Then, link those potential risks to the activities where they can act or where their impact can be sensed.
Now, considering those activities and risks, identify what process parameters or material/product parameters should be controlled to check if everything is OK. Then define:
Who will control those parameters;
When will those parameters be controlled;
What targets and specifications will determine if the activity is OK or NOK;
Wh at monitoring resources will be used;
Is there any need for visual samples to determine OK or NOK state?
Where will the control result be recorded?
Who will analyze performance trends?
Will work instructions be needed to help perform any of those activities, minimizing nonconformities and variation?

I hope this can give you a frame to start that project.

The following material will provide you more information about production control:
- ISO 9001 – Managing Production and Service Provision using ISO 9001 - https://advisera.com/9001academy/blog/2017/11/21/managing-production-and-service-provision-using-iso-9001/
- free online training ISO 9001:2015 Foundations Course – https://advisera.com/training/iso-9001-foundations-course/
- book – Discover ISO 9001:2015 Through Practical Examples – https://advisera.com/books/discover-iso-9001-2015-through-practical-examples/