As you said, keep the glide bars and clamps clean. I assume the clamps are also removable from the glide bars, so I'd clean the mating surface in their bases occasionally also. Examine the tension head and where there are moving parts lubricate them sparingly with a "dry" type of lubricant like silicone spray. Also, you should have a tension calibration tool and check the tension on your machine about once a month. Calibrators can also require adjusting and you need a verified set of weights for that job. I have a couple of 25lb. Olympic barbell weights that I had verified at a scale shop.