I apparently can discard the white/greyscalar ring.
Two points before you even get to adjusting the elevation angle.
1. 68.5 East is a linear polarity satellite in C-Band. You need to have the orientation of the two small probes inside the LNB throat aligned correctly at the correct polarity angle for the satellite. This angle is defined by your location, it is the polarisation skew angle, not to be confused with the elevation angle.
2. Personally, I would fit the scalar to the LNB, it will reduce the background noise and enhance the signal.
In addition, the LNBF should have the throat aperture at a few millimetres less than the focal length of the dish. However, the feed support arms and LNBF clamping arrangement should get it to within a reasonable tolerance of that distance.