We advise lubricating the guide rods of the Cable Column with a silicon-based lubricant.
To do this, pull the cable in and out while spraying small squirts of the silicone-based lubricant on the guide rods and the bushings of the top plate so that the lubricant is spread the whole way up the guide rods.
Once the weight plates are moving smoothly up and down the guide rods, wipe any excess lubricant that is gets on to the plates themselves but try avoid wiping the actual guide rods as this can just remove the lubricant that was added.
The stack should now slide a lot more smoothly and eliminate the sticking - this is completely normal and cable columns require this maintenance regularly to keep them performing at their best.
Example of silicone-based lubricant: