[Wavytone]

At 9m focal length you're going to visibly see the effects of:

A) atmospheric refraction, which varies as a function of altitude and is neither constant nor linear, and it varies by location (altitude) and weather conditions.

B) flexure in the telescope assembly which will also vary according to its direction (both on altitude and azimuth) if it's an equatorial or fork mount. The flexure problem includes flexure in all parts from the mirror supports, the tube assembly, the focusser, as well as the saddle, equatorial and equatorial head and tripod.

And you'd be surprised how much the scope flops and sags under its own weight - for example just try adding to the OTA the weight of a second eyepiece and watch the image shift. Then consider the mass of the OTA and what this implies for the sag arising from that.

You can roughly compensate for these by tweaking the drive rate (eg the King rate is an approximation to allow for refraction) but if you are after zero drift on this scale the only solution is to use an auto guider.