Establishment of an improved model for assessing criticality of waste in maintenance operation strongly supports the creation of sustainable manufacturing. However, contribution of previous maintenance engineering studies to above issue is very limited. If any, it is very few intended to create a model for ranking criticality of maintenance waste using risk management tool. In spite of the fact that utilization of risk appraisal tool has been introduced in earlier studies by modifying FMEA, some limitations are still existing and demanding for a better refinement. In this paper, an improved model for calculating the risk of maintenance waste using modification of FMEA is proposed. In evaluating risk criticality of maintenance waste, a new waste priority measure is presented via combining new additional dimensions extended from previous waste criticality evaluation models. In the new model, additional indices, the preventability and controllability scale of waste are included in an attempt to narrowing down limitations on using the detection indices only. An example on using the new waste reprioritization model for maintenance waste risk is provided. The proposed model offers an alternative perspective on evaluating the risk of maintenance waste and an improved model for maintenance waste alleviation.