The rear wheel was bent, So I had them replace it with a new wheel. While I was having them do this I told them about the shifting problems.
They replaced the rear wheel, used my cassette from old wheel, and now it basically skips and stays on the sprocket while under a load, like standing on the peddles and pumping.
This bike has less than 500 miles on it, and after researching this forum it seems the cain is worn or the cassette is worn. I looked at the teeth on the cassette and there is one that has a slightly rounded corner, but the rest of them are good.
Can you replace one set of gears on a cassette or do you do em all? Also, how do I remove the chain? I don't see the master link at all.