Flawed: Your intuition has served you well, and you find that the rods click into place as you insert them. The forge opens up, not unlike the jaws of a great beast, and a sliding panel in the back rolls to the side, revealing a small vault.
Assumption: Plonk checks for traps, and [Search check] finds none.
Everyone: Inside the vault, you find two sacks filled with old coins (one of silver, one of gold), 4 ancient gold ingots, four stoppered vials, a scroll case, and an adamantine plate shaped into a seven-pointed star, roughly six inches wide from point to point. This last item must be the schema.