Recently converted t' 13mm power, went unstable off t' rod and tumbled. Well, blow me down!  Motor wasn't seated all t' way because I friction fit it and it got stuck.  Couldn't get it in any further, ya bilge rat, couldn't get it out. Well, blow me down!  I'll try again with t' engine seated properly t' see if it flies stable or if t' 13mm conversion makes it a shelf queen.