Great update Nino with plenty of great advice.   Specially the tight switch stacks my first Em had a few loose stacks so I'd adjust the contacts play a few games then problems adjusted again played a few games then bam.   No Internet in those days so when I decided to pull the stack apart noticed they were loose as a goose never played up again.

As for the NOS plastic plunger all I can say is only you Nino only you