Thank you Andrew and Ben. I joined two of my old ankle weights and got it around the dew shield, but with an extra 1kg of weight. The guiding looks better than ever (in a short test), I suppose the mount does not have to "fight" the imbalance any more.
Considering that the Kmart ones are cheaper, Ben, did you use just one to go around? They look suspiciously similar to the ones I have here.
Regarding the back-weighting Andrew, not sure. It looks quite good what you did, as long as it does not shift. I assume that there is no dovetail bar on that side of the OTA, otherwise
this could help. Someone else may have better suggestions.