Change a string in a field for a number

Hi, from time to time In the milliseconds field( that is for numbers ) appears the string: "disabled", what Im trying to do, is that every time the string "disabled" appears, change for it the number "0" I have tried with gsub without results....do I need a conditional? how can I do this?

filter {
        grok {
                match => {"message" => "%{DATA:server}\s%{DATA:milliseconds}"}
        }

        mutate {
            gsub => [
                     "milliseconds" , "disabled", "0"
              ]
            convert => {
                    "milliseconds" => "integer"
                }
        }

What does the resulting event look like if you use

output { stdout { codec => rubydebug } }

Note that mutate does processing in a fixed order and convert comes before gsub, so you need to split that into two mutate filters.

It shows all the fields but not milliseconds, testing in grok debbuger, seems that DATA doesnt accept numbers, so the field doesnt even appears in the stdout, later I try this also without success

filter {
    grok {
            match => {"message" => "%{DATA:server}\s%{NUMBER:milisegundos}"}
    }

    if [milisegundos] == "disabled" {
            mutate {
                    replace => ["milisegundos", 0 ]
            }
    }

    mutate {

            add_field => {
                    "origen" => "alpha"
                    "horayfecha" => "%{hora} %{fecha}"
            }
            convert => {
                    "milisegundos" => "integer"
            }
    }

that trows a grok parse failure whenever it find the string "disabled"