In this paper we consider a maintenance and production model of a flexible manufacturing system. The maintenance activity involves lubrication, routine adjustments etc., which reduces the machine failure rates and therefore reduces the aging of the machines. The objective of the problem is to choose the rate of maintenance and the rate of production that minimize the overall costs of inventory/shortage, production, and maintenance. It is shown that the value function is locally Lipschitz. Then, the existence of the optimal control policy, and necessary and sufficient conditions for optimality are obtained.