Half-way through modding one of these. I haven't discarded the spring just flattened it out to give a light pre-load.
Managed to get 30mm of travel on mine

EDIT: here it is. Couldn't find a rubber band of the right size so I had to make a band from dressmaker's elastic (tried to get the elastic out of the wife's knickers but she wasn't in a forthcoming frame of mind

).
Advantages are that you get a much longer travel than by using the spring, and the elastic is a lot lighter in spring weight so there's no chance of pushing the readout along against the magnetic force when the spring gets bound.
Disadvantages - well it's very Heath Robinson but seems to work well. Magnets came from a hard disk and were cut in half with an angle grinder.