concerning my question about types of observatory...have found pretty detailed plans for a self-contained/revolving dome from BBC's "Starry Night" magazine from a couple of years ago--checked old CD's I keep because of interesting items and low and behold, set of plans. No doubt that RORO is easiest (and cheaper no doubt) but a dome is almost irresistible. At the very least, I can cost the thing up before I quietly change my mind after seeing the £ signs on paper. I fitted a Peterson set of ballbearings to replace the Meade plastic washers. Definitely more positive BUT still got some slack in the knob. So don't expect the bearings to work magic, cause the play in the focuser knob is in the connection to the mirror itself. Play in the rod to mirror connector hole is where it seems to be; have to work on how to shim it out. Just possible that a drop or two of Loctite bearing fit would eliminate any play-after all, there's no real strain on the connection. As if I hadn't got enough to do!