Digital BW, The Print

Hi all

I am desperately trying to clean a medium format slide that has become soiled. (The scan 
just has too much to deal with.) I have purchased some Film Cleaner by SDS Scanner Drum 
Service Gmbh but am still struggling as the solution itself seems to leave smears on the 
film.  Any tips or ideas? - other than shoot digital to begin with :-) 

Cheers

Steve