Lehner Question

[Sower]

I just got my 1940/10 hi-amp in the mail from Mike this last week and I noticed something that I wasn't sure about. When I spin the shaft by hand it will make a rubbing sound inside. Is that something to be concerned about? Did I get a bad motor? I hooked it up to a battery and speed control and played around with it (not in my CRT, just in hand) and it sounds great under load, but makes a little noise when you let off the throttle. What do you guys think?