My mouse wheel went 'soft' and stopped working.

I replaced the encoder but still it wasn't too good and I realised that the mouse wheel hex shaft that connects to the encoder was worn down.

That was when I decided to try and 3d print a replacement part..... and here it is.

It is working for me but you may want to tinker with it a bit more.

303 mouse is the smal wireless optical mouse design from China sold under many brands.

I hope this helps someone!