haven't ever worked on an EM but find SS repairs are pretty easy most of the time. the internal diagnostics got better with time. the dmd's are more complex but better diagnostics to even that up against the early bally SS. i have had the most problems with a TZ but reckon I've got it beaten now (I installed a PINLED driver board - magic diagnostics and much improved power regulation and flow). seems to have fixed all of the issues (the previous PDB had been serioulsy hacked). keen to get an EM to mess around with just to see how they worked. i think most people focus on the machines they played 'in the day'. Its funny but i played pins in two different eras (in my early teens when i wagged school - early 80's) and then again at uni in my early 20's (90's DMD's). i remember seeing EM's but can't ever remember playing one (I know I did) but it just wasn't as memorable as playboy and centaur!
