HP82143A Repair - Buzzing While Powered On

[cesarb94]

So apparently the printer actually works, the real problem was a jammed motor. I've removed it from its mount, spinned the rotor by hand a few times and now it's free and the printer is working. However the buzzing sound is still present and it it's volume gets higher when sliding the intensity selector towards "dark". I've replaced the small capacitor from the power supply circuit but that changed nothing.