The cabin-top (over the slider for the companionway) is an independent piece. It can be unscrewed from the boat, and worked on independently. Mine suffered from water intrusion from the various cleats and turning blocks on the cabin top. Once off, you can remove the slider rails and cover if you wish. My tracks were brittle, so I replaced them when I rebuilt the cabin top. Note: You need to keep an eye on any build up on the cabin top from the repairs. Otherwise the hardware from the cleats, etc. will interfere with the slider.
Ken
USA-45