Model 2 losing pitch/slower

[Model2]

https://youtu.be/MtUsjz5rKdE

This video isn't mine, but the Canadian Model 2 in Sebringville started slowing down and losing pitch a couple weeks ago. The station checked the power supply, and found no problems. They're going to take to take the siren off the tower for inspection.

Any idea what might be causing this problem?

[Unit of Civil Defense]

...Stator windings could be bad...worn rotor....worn brushes....don't know if it had bearings or bushings but they could be needing replaced due to seizing up and causing drag.