Headphones Monitors not dead after all

[Ser G. <simpliflying@gmail.com>]

Hello, good news, it was such a stupid thing.
Do you know the black, hmmm, ok, thing, the black soft thing which cover the speaker of the headphones? From outside it was not noticeable but I took off the circle which closes around the ear (no idea how is it called), and then I removed this soft sponge, and in its inner part it was broken and a part was touching the speaker, provoking a vibration which seemed to be of a damaged speaker.
I am glad I do not have to spend money!
Now I am listening to some basses in mono, and I notice that on the right side it is brighter, on the left more punchy.
Can this be a subjective perception as it often happens for the eyes (where one eye sees colors and light a bit differently)?

Ser