Washer shaking badly, why?

I have a Maytag top load washer. I tipped it on its side to see how to change the drain line. And since then the drum has started shaking severly. I didn't mess with anything while I had it on its side and I don't know if that is what caused it. But I thought it was just unbalanced so I adjusted the legs but it wasn't that. If it is the drum how can I get it to stop shaking.