Acoustically incorrect cooling?

Hey folks,

I come here seeking knowledge again. 

After listening to the wisdom of my fellow Agon'ers, I have been paying closer attention to the basics of system setup.

I have learned to experiment.  More importantly to listen to the differences.
So, after chasing my tail with absorption, minimal diffusion (varying size books on shelves behind listening position, etc.) I turned to DSP.

Ok. So now things are at a point where I am learning to recognize how each successive modification changes what I am hearing.

Now I am still just beginning to understand, appreciate and focus on what matters.
Instead of chasing the next, latest and greatest components, pay due attention to the listening room and it's potential contributions (and detriments).

Maghister, MC, OldHvyMec, Atmasphere, among others have been preaching things that I am just glad to have learned from.

So back to the point.  There was one last bit of glare (brightness, ringing?) that persisted in every room (two in the old place and three in the new place) I tried.

Cutting to the chase, I noticed that whenever anything brushes against, taps, etc. the heatsink fins on my monoblocks, the fins ring like a bell. 

I have each monoblock placed close to it's respective speaker (to minimize speaker cable length).
OldHvyMec pointed out that the steam radiators will ring like a tuning fork if I tap it with a piece of wood and to try throwing a blanket over it.

Worked like a charm!

Then I threw a moving blanket over each monoblock (just for a minute).

Problem solved!  I do not hear any ringing.

Now I know this is not a proper solution.  But quite a revelation (at least to a relative newbie like me).
I am curious if anyone else has noticed similar issues with ringing fins and how best to address it.

Thanks everyone!