Hello Christina,
Sounds like you may have taken care of things by servicing your R9. If you used the same ammunition that gave you the problem, put fresh ammunition in your magazine, rack the slide, and see how that runs. Pull the slide back fully and release the slide quickly, don't hold onto it at all. That way you will get the full power of the recoil system to push the round into the chamber. Have you ever cleaned the magazine? If it has been a while, pull the base plate off, and wipe down the inside of the can, the spring, and the follower. Then give it a spray of something like "One Shot" and let that sit for 5 - 10 minutes, wipe it down and then reassemble the magazine. Repeat the loading sequence and see how things go then. I hope these suggestions help with your loading issue.
Please let us know how you make out.
Sincere Respectful Regards,
Eric C. Rohrbaugh