I also had a problem with Lexmark drivers... Maybe this can help you
I have a Lexmark C912
Download the Windows driver for the printer
Install it on a windows machine (I used a win2k3 server)
search for PPD files in the Spool folder (mine was WINDOWS\system32\spool\drivers\w32x86\3 )
There might be a lot of them.
Now which one?
When you extracted the windows drivers in the installation it should have created a folder on your c drive called "lexmark" in there some ware should be a folder call drivers and in there some ware is a file called XXXXXX.PP_ (notice the _ in the place of the D )
This is a ppd file used by cups like a printer driver...
Back to the spool\drivers\w32x86 folder
in there should be a ppd file with the same name as the one you found in the PP_ (in the extracted "lexmark" folder)format
copy the proper ppd file from spool\drivers\w32x86 to your linux machine and use it in cups...
do not rename and use the PP_ file it doesn't work...