[serene911]

One side of the opening where each of the individual glass bevels fit in is part
of the wood frame,usually routed. the other side is where the glass is set in.
that side has the glazing putty against the glass to secure the glass into the
frame. Even if you strip the frame by sanding or another method you will find
the glazing putty will start to flake out of the frame. The cracking on the putty
is where it is worn out and failing. If the frame was taken down to raw wood
a oscillating tool can be used to remove the putty around each bevel piece.
You can then use a modern caulk or small 1/4 round trim around each piece
if there is room. Either way it is a ton of work. That is why nobody has tackled
it before as well as why windows like this end up in salvage yards or garage
sales for cheap.