I was hoping to roll back the roof tonight but the weather's been crap the last few days, way to much cloud and for what I need to accomplish would just be plain painfull.
But I'll take all the advice you all have provided and hopefully over the next day or so have some good results despite the light polluted skies!
As for adjusting the prism angle relative to the guider I don't think it is possible with the 8300 oag, the prism is adjustable in one direction only (back &forth), kind of glad really as I would have already played around it and stuffed it right up. The guider adjustment allows the camera to be moved in & out and also off centre as there is a bit of free play between camera and housing, this could part of my problem as well as focusing. Anyway let you know how it all goes, otherwise there should be a for sale add going up soon enough...
John