With the old glazing being hard as a rock and difficult to remove with a putty knife, I like to use an angle grinder fitted with 24 grit discs. It makes fast work of the removal, provided you've got a steady hand and don't dip into the wood.

I might use 24 to take most of it away and finish it up with 50.

The entire process is much faster with the grinder.

Of course, you can't go all the way to the corners................