It would take as much work masticking them as repairing.
It sounds like your parting bead is worn and the staff bead is in need of moving in.
Get a replacement strip of each for emergencies and remove the old ones with a paint scraper or similar blade.
You may be able to reseat the parting bead, that's the one in between the two sashes, to fit tighter to the top (outside) sash. Rub some candle grease on it and fit it tight up or replace as needed. If it is still too slack, put some self adhesive draught excluder on the top sash so it fits tightly.
The staff bead can go fairly snug up against the inner -bottom, sash again with candle wax. Fix the bead at the bottom with the sash down, then at the top with the sash up. Use 1 1/2" ovals if the old nails are stuffed.
These windows were designed to permit some draught. Draught excluder might minimise that.
(Look a bugger though.)