Here's what happened. TALL GRASS HAPPENED!..... So here in South Arkansas we get some pretty mean storms as spring pushes out winter. My clients thought lightening may have struck their antenna atop a water tower 160 feet up. Instead of climbing the tower (which no one ever likes to do), I decided to fly up and take some pictures of the antenna in question. No damage was found. So I bring it down, and since my clients are there watching, I decide to auto-land.... in tall grass.... against my better judgment. BAD IDEA. Of course it touches down, taps the ground, lifts back up 8 inches, and goes down again. But before it started to power down it tilted over and now one of the motors is locked up and screaming bloody murder. Seriously, it was pretty loud. Smoke begins to rise from the motor. Luckily I power it down and all is calm now. I let the motor cool down for a few minutes and fire her back up. All seems to be fine, motors running but not flying (sitting on a piece of plywood this time). I goose it and bring it up to eye level, making sure all props are plumb and level. All seemed pretty fine but about every few seconds there's a quirk. Like it jerks to one side real fast and then re-establishes itself. This all happened last week and I still have the quirk. So what is it? I haven't gotten over 10 feet high for fear of the obvious. My guess is the motor is damaged, not running the same RPM as the others, and maybe it's trying to correct itself...??? IDK? Any input would be greatly appreciated. I know there are upgrade motors out there. So if it were the motor, should I get a factory replacement or just go ahead and upgrade the whole bird? If so, any recommendations?