4 to 5 years MAX - this is pretty easy to tell fom the RUBBISH connectors and shoddy wiring that was used.

I agree - 5 years maximum.

Looking at connectors - Jones plugs in EMs have no estimated life span, yet IDC connectors in DMDs have a rated life of 5 - 6 removal and insertions. Williams System 4/6 interconnectors are the same - if not longer.

I'm not suprised that EMs have lasted this long, but if you asked the designers back in the 60's and 70's they were interested in turning games over, and their earning capacity - not if they would last 30 years +