Clean Film Scene Audio

I have a single-track sound file from a film scene that is being sabotaged by a constant mechanical hum. I need that hum lowered to about 25 to 30 % of its current level so it reads as natural room tone rather than an abrasive distraction... (Budget: $50 - $60 USD, Jobs: Adobe Audition, Audio Editing, Audio Engineering, Audio Mastering, Audio Mixing & Mastering, Audio Processing, Audio Production, Audio Services, Music, Sound Design)