Hi all, 

Firstly I've made a lot of posts over the last few days on varying issues, so I'm sorry if I'm 'spamming' up the forum in any way, just having a few issues getting off the ground and looking to draw on this excellent community for advice. 

My issue is with ESC calibration. I have Mystery 30A ESC's, and I complete auto calibration successfully (two beeps with throttle up, put throttle down a further two confirmation beeps). On applying throttle all 4 motors spin up simultaneously, and as far as I can tell at the same speed. 

When I disconnect the battery and try again later, the following happens. The ESC's arm after 20-30 seconds with two confirmation beeps. This is all apart from motor 4 which does not appear to arm at all. When applying throttle three of the motors spin up, no response at all from motor #4. If I go through auto calibration again motor #4 will calibration successfully and once more for the duration that the LiPo is connected they will work in unison. Disconnection / reconnection recreates the problem. 

I've switched the motors around and it seems to always be output pin #4 not arming, independent of the ESC's or motors attached to it. 

Any ideas? Or am I forever going to have to complete ESC calibration every time I turn it on? 

Cheers.