I'm glad that little fuse solved your problem (mostly)!
A 1/4 amp fuse is a touch too large. Yes, your displays will work but they are over-fused and exposed to risk of over-current. I used a 1/4 amp fuse temporarily for troubleshooting but I really don't recommend this practice. Get the right one installed ASAP.
This site has your fuses and many other parts:
Still talking about your displays. The missing digit is an easy fix. I used this article to track down the offending parts:
Scroll down to the part dealing with the level shifters.
As for playfield coils:
Use the flipperwinkel guide I posted above. Section "3i" will get you started. If it were me, I would start at the rectifier board. I have a 1984 system so it may be different.
If we have the same board (AS-2518-54):
You should find +43vdc between TP5 and Gnd
This circuit is protected by a 5A fuse labeled "F4"
Hope this helps.
Another handy thing to use while troubleshooting your coil circuit is to rig up a circuit breaker (sized appropriately for your circuit). Much better than "smoking" fuses while you look for a problem. Also, don't risk using too-large of a fuse while troubleshooting. You're likely to "smoke" something downstream and create a much larger problem.