About the pop-bumpers: I think firing the coils in testmode is using different 'logic' from firing them in gameplay (unlike later games). You do know wiring to the coils from the PCB and the coils and fuses are ok, but you'll have to look at the switch that activates the coils via (there're 2 switches at each Road Kings pop-bumpers! 1 for the switch matrix when the coil fires and one for driving the coil).
I'm not sure the above schematics from the manual is accurate though.... compared with the one below, which seems to make more sense to me:
Maybe a bit hard to understand (I know I haven't worked with that part of the pcb for quite some time and I'm not sure....). Easier: I'd start by checking if the pop-bumper-switches close if the ball hits the popbumper-skirt.