I have a fc40 that's about a week old. The other day when I was installing prop guards I noticed one of the motors is tighter than the other 3 . Is there an easy yet cost effective way to loosen it up ? It doesn't seem to adversely affect its flight performance much if at all. When in initial hover it will slightly spin like I'm inputting rudder but the flight board seems to compensate for it and it will correct itself.Thanks