I just ran my first carving with, I believe it's an "A" machine (SN begins with A?). Anyway, about half way through it started making extra noise like something was vibrating a lot. I stopped it, blew everything off including the motor in the back, and started it up. It was fine for about 2 minutes then started making the noise again. Sounds like it's coming from the motor. I just let it run cause I figured if something broke then I would know what to fix. Any ideas what to do?

Also, the carving I made some of the smaller elements where not very sharp. I thought maybe it was because I used poplar. Does the wood type make a big difference? Thanks!!