Not familiar with "Op amp" other than an term for single-chip "operational amplifiers". There several products I've come across that use op amps to do A to D and D to A conversions but that's just conversions, not scratch/click repair.
For short scratchy selections I have used Audacity (
Click Removal - Audacity Wiki
For years I used SAW (Software Audio Workstation) on an old PC (version had would work with Windows 98 but nothing newer). That one was very good for manual repair but I recall one 2:40 piece that took me about 15 HOURS to fix. It was worth it, though. I haven't found any updated versions so this one probable should just be scratched off the list.
For extensive repairs Adobe Audition does very well but it's definitely not free!. I don't own a copy - just don't have enough use for it and have access to it with a little inconvenience on the rare occasion I have a need.