I recently had a customer ask if I could add weight to his putter. He had tried a heavier model and liked the feel much better. Adding weight can be accomplished two ways. One is to add lead tape to the putter head until the desired weight is reached. The other is to remove the grip and pour lead powder down the shaft and secure it with a cork. Using a swing weight scale during the process enables you to create the desired swing weight the customer wants.
Keep in mind shortening or lengthening a putter will alter the swing weight as well. Shortening a putter's length will decrease the swing weight of the putter - lengthening the putter will do the opposite.
If you have a question about club repair or other equipment topics please email me at firstname.lastname@example.org.