Now might be a good time to remove the carb, take it completely apart, and soak it in CHEM-DIP for about a week.
After you remove it from the CHEM-DIP, rinse all the parts with spray cleaner and blow through all the holes/passages with compressed air. Then, go to your IH dealer and by a rebuild kit. I would suggest that you visit Rudi's server and read the articles about the IH carb submitted by Lurker Carl.
Hope all this helps in some way.