HELP? Elektra Casa a Leva

[buna]

Hi - l have a 1979 Elektra Casa a Leva - the portafilter has no retention spring so the puck & basket flies everywhere when l knock out the puck!

Does anyone out there know someone that may have a metal lathe and the skills to be able to cut a groove on the inside of the portafilter to hold in a retention spring?

Happy to pay for the service of course.

thanks.