below is the circuit that isn't working.
the green highlight is ok because payout works. There's something wrong in the yellow highlight path.
suggest using your voltmeter ... put one probe on orange wire 70 on any handy 50V coil (any of the coils except the bell). Put the other probe anywhere along the yellow path.
In this case, I'd suggest the spot marked with the upper red arrow since you can flip down the top panel and easily get to both wire 70 on the coils on the odds unit and blue/white wire 25-1 on a pin switch poking out over the ratchet/gear on the odds unit (see below pic of an 809-ZT - you can poke wire 25-1 on the wire or the blade). If you don't get 50VAC (typically around 53V), your problem is up the circuit on the diagram or you have a plug connection issue to the top panel.
if you do get 50VAC on wire 25-1, then the lower red arrow is a black/yellow wire on the handle release relay. You'll probably need to pull the reel mech to access and you need to measure with the reel mech in, so you need to clip onto the wire. I use a jumper wire with alligator clips and clip onto the spot I want then leave the other end dangling out the front then shove the reels back in.
if you do clip a jumper onto wire 83-1 and replace the reels, you can also touch the other end of the jumper to yellow wire 30 on the coin switch and the handle releae relay should trip. If it doesn't, the switch that should be connecting 83-1 to 52-1 is not closed when the handle release relay is latched (reset) or the release relay coil is bad.
on the bottom of the below is the wire color chart ... once you figure out how the wire id numbers map to colors, you're most of the way to using the the schematic to find issues. The important thing is the -xx suffixes. Since there's a limited number of color combinations, the same color wire may be used in multiple circuits and they aren't electrically the same wire. e.g. 83 and 83-1 are black/yellow and look identical, but they are not connected together. Exception is yellow wire 30 is always wire 30 everywhere unless it's a thin jumper wire (jumper wire colors can be anything) ... there is no 30-x wire. It's a good bet that a solid orange wire is wire 70, but since it mostly connects directly to coils it's kinda obvious.
other things ya need to know:
- dashpot switch is on right side of the reel mech by the air cylinder
- coin switch is the microswitch under the coin mech on the door
- coin relay is on left side of reel mech and the bottom/rear
- reel mech A,B,C switches are above the coin relay
- odds unit is on the panel in the upper compartment
- payout relay is usually on the hopper
- plug connections are not shown on the schematic and are often the problem. You can clean the plug pins with a scrub pad or dremel with a wire wheel. Don't worry about the sockets unless there's obvious and bad corrosion in them as the plug pins typically will scratch thru surface corrosion
oh yeah, if you are using continuity/buzzer to try and find the problem, it will find open circuits but not necessarily poor connections. Look at the ohms reading for almost zero ohms since it will tend to buzz for stuff below 40 ohms or so ... and there's lots of roundabout circuit paths thru coils and the transformer that are less than 40 ohms. If you see more than a couple ohms, you don't have a good connection between the meter probes or the probes aren't making good contact with what they are touching.