Hi Richard,
never tried it myself as my 2c's boot lid piston is a bit the other way, and you have to hang onto the boot lid when opening, but as it's a spring, not hydraulic, why not remove it then take the clip out that retains the innards and see if you can either stretch the spring a bit, or find a stronger replacement. possibly packing with a spacer inside might do the trick.
The diagram from the Tavoli is for the series 1 Berlina, the series 2 is similar but although the tavoli shows the same retaining clip, it doesn't show the exploded view.
Just had another thought that perhaps the insides are rusty and a drop of oil might improve things.
Brian
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