I need to replace the topping lift and also replace the sheave on the top of my mast. When I sent somebody up to replace the anchor light, he took a picture of the sheave. Looks like maybe the same bolt goes all the way through the masthead and holds the sheave for both the topping lift and for the main halyard? Has anyone every done this. It looks like it may be doable with the mast up but don't want to pull a bolt and drop the main halyard sheave at the same time. Any perspectives from looking at the picture.