First let me say hello and welcome to Cloudy Nights...
Basically you have to balance the scope in two positions, vertical and horizontal. This is a teeter-totter problem. The basics:
If the tube is placed horizontally, then what matters is the distance the weight is from a vertical line through the center of the altitude bearing, i.e. the balance point. It's a center of gravity problem, so it's the weight times the distance from the pivot but only in the horizontal direction.
Think of the teeter-totter, it doesn't matter how tall each person is, only how much they weigh and how far they are from the pivot. If one person weighs 200lbs and the other person weighs 100lbs, then the person how weighs 100 lbs will have to be twice the distance from the pivot to balance.
Once you balance the scope front to back, then you place the tube vertically and adjust the distance the counterweights are from a vertical line through the center. You can move the weights in and out without affecting the horizontal balance but if you add or subtract weights you will have to rebalance the horizontal axis.
These adjustments should be done with scope free to pivot.
Since the scope is sinking at normal altitudes, it suggests that the front to back balance is heavy in front, it appears that way to me in the photo that is the problem. There are three choices:
- Move the finder rearwards, closer to the altitude pivot until the scope balances. If you can do it, this is the best solution.
- Add more counter-weights, you don't want to do this unless you absolutely have to.
- Move the counterweights reward, away from the pivot point. It appears they are as far back as possible.
That is a lot of weight you are adding.. it may result in vibration problems even when it is balanced.
Hope this helps.