Fred, I recalibrate the autoguider each time I move to a different area and autoguider settle is on. Yes i'm using autodarks. I do hear what you're saying Fred and I'm really listening hard, true. I'm just having a hard time working out why on one night I can get 35 clean shots in one area (eg ngc3621), come back the next night to an area just south of that (NGC5128) and get 35 useless shot. Add to that if I flip the meridian, calibrate and guide over there for a few minutes, flip back to the original side I can guide all night without a problem. However I am taking your advice and looking at how i can fix the guidescope hard to the imaging OTA and looking very closely at how I can make sure the guide camera is a immobile as I can make it.
Robin I have very very little misalignment and running a 5 min unguided shot shows only a few pixels drift in dec and only PE in RA, I don't think it is likely that the problem is in reacquiring the star as in that short a period it won't have moved. Of that I am confident. I have taken the GPUSB out of the equation a couple of times by guiding directly from the guider relays straight to the mount. It didn't make a great deal off difference so in that respect I'm confident of using the gpusb. I have also used it via Maxim and Phd, and while phd still has a few question marks hanging over it I'm fairly happy with the GPUSB. I could try ASCOM but I've not used it before in any significant way and I'd rather not try to lean something new while I'm sorting this out. Maybe one day.
I've also checked the guide rate and it is set to 1x sid. Once I've finished processing them I'll upload some shots from over the past couple of weeks with their details on equipment/hardware/software combos. I must say that I was very happy with last nights efforts after the initial swap from one side to the other.