jack lalane power juicer burning smell

i've had it for a few months, and my mom got it from a friend who i'm pretty sure did not use it. anyway it has been working fine up till lately: once a couple weeks ago it made funny noise and had burning smell so i turned it off and figured maybe i put blade in wrong, but today same thing happened cept this time it was working fine until about 2 minutes into juicing......... could it be an uneven counter top?

thanks for any input, Ron