Nofollow links to resources used to save bandwidth?

[sbetzen]

I have a site on volusion, www.ecowindchimes.com. Until recently I was doing fairly well (top 3 for keyword(s) for 6 years) in serps. I was hit by the an update around july of last year, and did a full page redesign in november. My site has been losing ranking for its main keyword "wind chimes".
One change I noticed is that no-follow was removed (when the designers added a lightbox popup for the sound) from the many many links I have for my sound files of the wind chimes (I house them on a separate server to save bandwidth, which is expensive at volusion). The webaddress the sound-files are on doesn't even have a page... it is just there for the files. (there are ~100 files linked to on almost every page of the site where a product listing shows).

Should I go through and no-follow all of these links again? Is that hurting me?
I suspect it is, but it is a lot of work for nothing if that is not the problem.

[FedeEinhorn]

Those sounds are yours, therefore you don't need them to rank in SERPs as long as your Website ranks. Anyway, Google does not display "sound results" so I don't think following or nofollowing those links will do much difference, I don't think that is the problem why you could be loosing your rankings.

[sbetzen]

Will Google still treat them the same if they are on another domain... even on another server. Does Google know they are mine if they are on different domain/server? I was concerned that I will sending out link juice on every page of my site with these.

[FedeEinhorn]

Are you using a CNAME of your main domain for that server? Like sounds.example.com? You should, if you aren't. I don't think pagerank can flow to a sound file. But I am not entirely sure, tho.