SR9C recent difficulty chambering first round

I have had my SR9C for a year and shot between 500 and 700 rounds. It gets cleaned (Hoppes) and lubed (RemOil). I have had no problems of any type until the last two times I took it to the range, when I had consistent problems getting the first round to chamber when initially racking the slide. This was with both magazines. and with both steel and brass ammo. Once the first round is in, it shoots fine. I had thought that maybe the mag springs were not pushing the rounds up high enough? I store the mags empty and I usually only load 5 at a time so I don't go overboard wasting ammo. Any ideas on that one? I contacted Ruger, and they thought maybe I was not letting the slide snap back hard enough, although I have not had the problem before whether I let it snap back hard or controlled. And when it snaps back hard, it feels to me like there is a little bump as the bullet either goes from mag to ramp or ramp to chamber. I checked the ramp with a magnifying glass and did not see any burrs or defects. They did offer to take it in for repairs if I continued to have the problem. I put a little auto polishing compound on the ramp, shined it up by hand, and cleaned and lubed it again. Any other thoughts before I try it again? Thanks.

That's pretty much what Ruger suggested. I will see how it works after the cold snap passes and I can even go to the range.