Have seen several threads on motor upgrades, issues etc .... But have not seen much on actual replacement requirements when trouble comes .... I have a single motor on my P2V that has a small vertical give or loosness to it, other three seem fine and feel rock solid no lateral or vertical give at all (have been wondering if this one bad motor is giving issues on slight tracking issues I have noticed) as have been down the road of recal IMU, compass boogies etc etc etc ..... and could find no real outstanding problems except this one motor so thought might be my prob ?? My question is I have ordered full replacement set of stock motors, but am unsure whether I should just replace the "dodgy" one .... or replace full set of 4x at once ?? Craft flies ok now and holds position etc fine with GPS etc (just have slight slide when close to the deck at times ??) .... am just worried about things if this "dodgy" motor gives out when up and flying I may lose entire setup to the old gravity/ground equipment impact rearrangement ??? Anyone been down this track ?? do you just replace faulty motor or replace entire quad set ?? ... would appreciate any and all comments.