Old Chicago had been working fine - tuned on this am- credits shown - push of credit button - nothing- reviewing startup sequence but there is none- no activation of coin or credit relay - coins which added credits via either chute normally get "rejected" as coin unit relay on door mechanism not energizing either - only issue since previous day/ normal function was raised machine approx. 1 inch in front to adjust legs height slightly but other than that no sharp movements etc. - Tilt and delay relay not energized - Playfield and Backlights all lit - fuses all good.

Was thinking coin unit switch? But neither is adding credits which would seem odd - but curious for other suggestions. Again, this is not a question of certain features of startup being irregular- its no startup at all all of a sudden. Did all the usual "easy" things- checked and reseated Jones plugs, fuses, etc. Thanks for thoughts.

Thanks for the comments/suggestions. Mark, the lock relay is energized when power gets turned on- it is the only relay dong so. Going to try and use alligator jumpers per Howard to try each circuit/switch as best I can determine - a little unsure of the source /common lead even after reviewing Howards links but will try - thanks

Thanks Howard for spending some time with me - and getting me comfortable with the circuit tracing procedure outlined above by both him and MarkG. Using the alligator clips/jumpers was able to systematically rule out several possibilities on the way to determining one of the coin chute switches ( different schematic than the main system one, BTW) had worked loose and was preventing the start up sequence from initiating. Was fortunate to start at the "bottom" of the circuit on the schematic - and got to resolution pretty quickly. Working normally. Thanks again!