Footstrap hole gone! How to fix it?

[AlexWind]

Hi everyone, after a year I tried to change my back footstrap position on my iSonic 122 from the middle hole to the "all back" position in order to get more speed, as someone told me.
The bad thing is that the all back hole is gone! The screw is loose and it gets out easily!
And the strange thing is that I've never used that hole before!

What can I do to fix the hole permanentlly?

I was thinking about getting a bigger screw, may it help?

Any other solution? I found some topics on that theme in the forum but I can't find a "definitive" answer to that..

Thanks in advance, cheers