Hey guys. Last fall, I replaced the propellers on all sides of my Mavic Mini. I flew it once since then before the winter weather came in. The weather is starting to warm up now, but I noticed that the back right motor with the new props on it is really hard to turn. Theres no scraping sound or anything, theres just alot of resitance when I try to manually rotate it unlike the other ones. I can't remeber if this was already happening when I replaced it and flew it once. But I don't want to test flight if it could cause an issue.
Thanks, Aidan.

Hello there Aidan. I am sorry for the trouble this has caused and thank you for reaching out. May we please know is you are receiving any error message on the DJI Fly application and kindly please post a short sample video showing the issue for us to see and can assist? Thank you.

I had this once in one back motor. Close look at the bearing and shaft revealed rust. I did have a flight in a humid city before I packed it away but seems odd just one motor went bad. Perhaps a drop of liquid got in that motor. I requested DJI to replace that motor but since it was also sent in for barometer fault they replaced the whole unit under warranty. Check if you got rust. It could be sand too which could be blown out with a jet of air. Something is blocking the motor for sure if it feels harder to turn.

Guorium Posted at 4-8 01:40
I had this once in one back motor. Close look at the bearing and shaft revealed rust. I did have a flight in a humid city before I packed it away but seems odd just one motor went bad. Perhaps a drop of liquid got in that motor. I requested DJI to replace that motor but since it was also sent in for barometer fault they replaced the whole unit under warranty. Check if you got rust. It could be sand too which could be blown out with a jet of air. Something is blocking the motor for sure if it feels harder to turn.

I don’t know if it would be that, i got a bunch of stuff fixed on my mini last year and I’m pretty careful with keeping it out of rain or humid

AidanDroneFan Posted at 4-8 03:32
I don’t know if it would be that, i got a bunch of stuff fixed on my mini last year and I’m pretty careful with keeping it out of rain or humid

If it doesn't turn freely I would deem it not safe to fly.  Normally, this is an indication of something, even really small to the eye, being stuck in the windings or possibly a bearing going out.  I have replaced two motors on my original Mini and it's not really hard to do if you have steady hands and a small tip soldering iron.  Plenty of YT videos on how to do this.  Just keep in mind the MODS will tell you they do not recommend DIY projects.  

I'd try blowing out the motor with high pressure air and then if that doesn't help it to turn freely by hand it will be time for a replacement motor.

if you dont have warranty or repair shop near you, just use air blower and blow motor (not too much and not too close) afterward put some (not too much!) wd40 or other rust remover in motor, give it few manual spins, let it sit for few minutes and spin again. power the drone and app, if there is problem app will put out an error message. if everything is ok just start drone but don't fly, put both stick out and down to spin motors without drone taking off. Lett it spin for few minutes. If ok do hover test