One of the tricky bits about using cable columns is that you often lack the precision to make small adjustments to the working weight. Sure, some brands have fractional adjustments, but more often than not you're stuck with whatever increments the weight stack climbs by... usually 10 or 15 pounds. If you're working with nominally lower loads, especially, those jumps can be far from ideal. So what to do?
Here's an easy solution that I've come to call 'hacking the stack'. Essentially all you do is add an external load to the weight stack. On the left, we've threaded the pin through a change plate. On the right, we've added a small dumbbell on top of the stack. It's not the prettiest solution, but it's the best way to split the difference between increments when precision is a must.
For the record, I'd generally recommend the method on the right, if you have a choice. Different brands have different pins, and while I've never seen it be a problem before it's possible that the pin might not sit correctly if it's not fully pushed in.