Runtime Monitors observe the execution of a system with the aim of reaching a verdict about it. One property that is expected of monitors is consistent verdict detections; this property was characterised in prior work via a symbolic analysis called symbolic controllability. This paper explores whether the proposed symbolic analysis lends itself well to the construction of a tool that checks monitors for this deterministic behaviour. We implement a prototype that automates this symbolic anal- ysis, and establish complexity upper bounds for the algorithm used. We also consider a number of optimisations for the implemented prototype, and assess the potential gains against benchmark monitors.