This is part of what I am working on just now. This the bottom half of a circular window - 1600mm dia. - for St Serf's Church in the Woodlands area of Glasgow. The upper part only required a few replacements and re-attaching tie wires for the two saddle bars.
The image above shows the glass partially cleaned and removed from the lead. Except in a few cases where the glass was too broken up to hold together, the broken pieces were taped together to act as patterns for the replacement glass. The broken glass has had replacements cut. The glass pieces are now ready to be placed in boxes to await their turn in the leading process.