If the part can be replaced, then your liability would not exceed the cost of replacement (part cost plus installation). If the landlord prefers to spend more to purchase a new stove, the additional cost is on him.
Is it wear and tear vs. damage? If it is ordinary wear and tear, then the landlord should not charge you -- but I cannot comment on the scratches, as I have not seen them and do not know how they were caused. As for grease damage, if the damage resulted from ordinary use with appropriate clean-up, then that should be ordinary wear and tear, but if you were using the stove unconventionally or the problem is that the grease was left in place or allowed to build up when prompt cleaning would have prevented damage, the landlord may be able to claim that the stains are damage.
Your landlord is required to follow California's security deposit law, so making up fees and charges is not an appropriate means of estimating the cost of repair.

