Paul,
Since carpentry was my first career I have a couple tips on
tightening loose hammer handles. First hold the hammer by the handle
with the head down and hit the end of the hammer handle a few good
raps with another hammer. This will usually tighten up the hammer
nicely. If the hammer handle is a split type and there is room for a
wooden wedge you can carve one out of whatever hardwood is
available. Wooden pallets are usually made from hardwoods and are a
cheap (free) source.
Rick Copeland
Silversmith and Lapidary Artisan
rockymountainwonders.com