Just do an online search, they are all over the place, at various price ranges. If you buy a 60X lighted loupe you can buy them for as low as 2 bucks, buy a few, it is cheaper than buying new batteries, they use coin type batteries and last a long time, as long as you turn them off, when not in use.
Tape protects the spine, because typically, new guys do way too many laps and needlessly wear the spine and change the bevel angle permanently. You can wear the spine so much that the thin blade angle will not hold an edge.
The bevel angle is actually pretty forgiving, most vintage razors have some spine wear, so a layer or two of tape, corrects for that as well as, prevents further wear.
When and if you get into restoration and have put many hours into sanding and polishing a razor and spine, it is a shame to grind a freshly polished spine on the stone, and it is especially a travesty to do so needlessly on a nice razor.
If, as in your case where you are most probably, very close to a fully set bevel, an extra layer of tape will increase the angle and quickly set the bevel. You can drop back down to a single layer, if you like, but for most vintage razors with some wear, I find 2 layers of tape works very well to approximate the original bevel angle, close to 18-20 degrees.
If you bevel angle gets too thin, (from Spine Wear) the edge can be more fragile and prone to chipping. It has nothing to do with sharpness except at the extream.
Jointing is a technique where you straighten an edge, by lightly running it against the corner of a stone, abrading away any ragged or lightly (Micro) chipped metal from the edge, much like Jointing a board edge straight and true, with a Jointer Hand Plane or motorized Rotary Jointer.
Once the bevels are flat and in the correct Bevel Angle, they can easily be brought back to meeting in 10-15 laps, depending on the stone and pressure use.
Here is a video of how to inspect the edge and what to look for.
Here.
Make sure you are under a bright light or out side in the sun.
Just do an online search, they are all over the place, at various price ranges. If you buy a 60X lighted loupe you can buy them for as low as 2 bucks, buy a few, it is cheaper than buying new batteries, they use coin type batteries and last a long time, as long as you turn them off, when not in use.