Ventus 2 undercarriage?

The undercarriage lever seems reluctant to stay in it's detent with the
wheel down - it'll pop out with the lightest touch and the wheel has been
known to retract, going over a bump.

One option is to push a wooden wedge against the lever, to hold it in
place,
but does anyone know if there's a better fix available? I believe the
Ventus
3 has a spring to hold the lever outboard - is that an option for fitting
to the
2?