The only real way to solve issues like this is a step-by-step reconciliation between the old model and new. Each assumption and calculation must be tested to co

The only real way to solve issues like this is a step-by-step reconciliation between the old model and new. Each assumption and calculation must be tested to confirm that they replicate the same output. This is extremely difficult if the underlying structure/assumptions are different (e.g. monthly views vs. transactional views, etc.).