How to decrackle an audio file?

[Wire57]

Hi everyone,
I keep having troubles with some older piece, one of the audio files has a lot of decent crackeling. Maybe when I did the thing first, years ago, I did not check if there was some clipping in one of the files I used for composing the one which causes trouble now.
I had tried out quite a lot of things, but the crackles seem to be in the mixed file and cannot be avoided by any EQ or limiter. Also, decreasing track loudness does not help.
I even had used Audacity's decrackeling tool, which did not remove any of the crackles. (As if the crackles were not in the file, but are created while playing the file.)
Is there any relyable plugin available which I could insert in a ProTools session?
(Of course I am not looking for the mose expensive one.)
Thanks.