I decided to have a few flights today having not flown since March. After booting up the craft a P2 and starting the motors the rear left one was stopping and starting while the other three were ok. I stopped the motors and fiddled with the affected one. It turned smoothly without any roughness or noise. But still would not run properly. I tried again and took the prop off and replaced it. This time it ran ok. And in fairness the motors all ran smoothly thereafter and I had 3 10 min flights. I mostly kept the craft low and near but did push the craft quite hard in all directions and did finally ascend to 100 metres and about 90 metres from me. So I am hoping it was just a bit of dirt or something in the motor rather than anything more worrying? The only other issue I also had for a short while the FPV screen blanked out completely as if it had been switched off. And them a few seconds later came on again and was fine apart from the usual strobbing interference I have always had. Should I be worried at all? Certainly my planned first flight over the English Channel is postponed for the moment! When not in use I keep a dust sheet over my craft.