At a grain elevator, I have a 480 volt 7.5 HP motor on a VFD. This motor is running a unload pit drag. Lately, it has been intermintently tripping out the drive overloads on start up (at times under load, other times no load). A week ago I showed up and opened up the drive to find it absolutely FULL of grain dust. We blew it out, cleaned it up and it started to run just fine. Now I'm being told it is doing the same thing. I'm on my way out the door to go troubleshoot it...this time I will disconect and meg the windings to check that out, I will also isolate the drive and check out the amperage. I'm wondering if the drive is shot? Any ideas and comments are much appreciated!