The trigger is being behind in week 20. The question now becomes what has caused the tooling problem and how fast, or whether, it can be resolved. I have seen projects which could not proceed for one reason or another. Usually it is a new process or material that does not perform as expected. The customer was informed, and in several instances came to the potential supplier to discuss. I have seen this in tooling for metal forming, for example, where a die would not perform as anticipated (especially deep draw where the company tried to use too few progressive dies).
From your example it sounds like you should be discussing the issues with your customer and reassessing the project.