Enamels are by far the easiest paints to work with... a red + yellow will always give you a true orange... this isnt the case with arylic lacquer or any other acylic based paint as they dry differently... acrylic lacquer make " mud" most of the time unless you have lots of base tones.... enamels are always true to colour.
But... and here is the downfall.. they take a long time to dry and you need to allow at least 24hrs before applying another colour or sanding back... in fact for sanding back... 3 days till enamel goes hard and is still not rubbery.

Secret to matching your colour is to get a red that is the same tone ( i cant explain tone... its something you have to learn, its not light or dark... its the same colour... different tone).. to get this though i can guarantee you that you will need yellow ochre as its this that will match the off tone that the linseed based finish has decayed to over the years. It is impossible to match any colour on a pinball without this base.

What you need to do is mix a colour and apply a tiny blob on the PF... look at it.. is it too red... too blue... too yellow, then by adding tiny bits at a time of the colour you are missing yiou will get close... when you get to the pioint that you think im kinda there but im too bright etc... add yellow ochre.
Simply speakinjg.. youve matched the colour of the original screen paint, but now you need to match the decay of 30+ years of yellowing that has occured due to the linseed base clear.

This is how you do a touch up... you dont match the paint.. you match paint + linseed + 30 years./

Good luck, but with ths info.. you should get there