I bought a Drillmaster 69474 7-inch sander/polisher from Harbor Freight this morning. When I run it, it takes a little while to get to full speed, which I understand is normal. The disc also wobbles quite a bit, and the whole thing seems to run a bit unevenly. Is this intentional, or should I take it back? I have the unlimited replacement plan, so exchanging it would not be a problem. This is not a DA btw.