A strange problem... {csv updater}

I lost many of the images associated with products after the last time I used the .csv price uploader. Upon further inspection, it seems that that the products which product numbers used to be 0xxx (0958, 0832, etc.) now have omitted the leading 0 and are now just xxx (958, 832, etc.).

This makes it so that the products' image reference is non-existent, as 0958.jpg exists whereas 958.jpg does not, leaving me with broken image links.

Upon a recent change to the server, I should also include the fact that I've had problems with glitches with the file permissions. At first, the .csv updater didn't function at all until I set the right file permissions to the "/csv" and "/csv_importer" directories. I'm tempted to say this problem is another file permission issue, but I'm frustrated in finding exactly which files are in question. I searched the whole server for "csv" folders and files, wondering if I need to set their permissions to 755 or 777, and if there are more files which this importer uses that also need permission changes.

Thanks in advance if you have any advice.