First, I would like to appologize for the post with the address for spline. Yes it was a good deal, and it did fit well, but the window that I took my measuements from was a replaced window of the wrong thickness! So I did order a new pane of glass, and 90' of spline from Vintage Trailer, which is a good quality, with a good fit. So then, starting from scratch with new spline? Go the extra mile and replace the Butyl tape as well. After removal of dried and cracked spline,I used a tool used for cutting acrylic to separate the glass, from the butyl tape. Use caution not to pry the two, because the glass as thin as is is will break! I took some WD-40 as a lube against the tape sticking to my knife. By cutting along the glass, parallel with the glass, and tape, you can slowly start to separate the pane of glass from the frame. Once removed, clean all tape from glass, and frame. Replace the tape into the groove on frame. Then I took (2) 1" pieces of spline, and cut the part which seals against the glass, in order to use as a base for the glass to set on , to guarentee proper alignment, before pressing glass against butyl tape.(Photos to follow) Then cut a 45 miter into the spline, paying attention inboard and outboard side of spline. After measuring frame, I added an 1/8", because you can compress the spline a little bit, and also the fact that the spline will slightly shrink over the first season. After all of this , and your spline is in, Take a small amount of vulchem, and place in miter joints, to tie each miter together, so no gap will appear when spline shrinks.