Many years ago (circa 1994), one of the levers of my cabin-top line  stopper broke off, but there were still enough to use. When another one broke in 2020, I decided to replace it with an identical  new one that I had been carrying around sine the 1990s.

It was through-bolted to the thick plywood/fiberglass roof of the pilothouse. Underside of the bolts could not be accessed without removing the vinyl-covered  plywood interior trim panel. and an impossible job to remove and replace on my own (this was at the height of the Covid Pandemic.

 Instead I decided to open a hole in the trim panel and later cover it with a small access panel. To locate the area for removal, I drilled though the edge corners of the old line stopper with a long 1/8th inch drill so I could mark the trim underneath. Using a razor blade I opened back the vinyl and then used multiple drill holes and a Dremel® cutting wheel to cutt through the plywood panel.

Then it was an easy job to remove the nuts holding the old linestopper and replace it with a new one using the original bolt holes.

It only remains to make an aesthetically pleasing underside trim cover (polished wood?) The original guide holes were plugged with 3M 4000 to keep rain from soaking into the plywood of the cabin roof.