I've been through some manuals making notes on the coils used when I had nothing better to do, I don't see any reference to the coil in any of the manuals I've looked at so far except the Miss America '75 and Malibu Beach, both of which note it's a FD-30-1300, the old number for this coil was E-184-248. Action Pinball's web site (out of Salt Lake, I think the guy's name was Ray years ago) says it's 22 ohms.

Wiper 20A sits on top of the cam on the search disc. The cam lifts a small stack of switches (A and B) which are closed when the wipers are at index. The switch should have no bearing on your issue.

Continuity may not be enough, you can get positive continuity but a drop in voltage will cause a problem, so you'll need to run the voltmeter and see if there's a drop somewhere. The tilt relay L1 needs to be closed as well.

The switch under the "R" button can get really crudded up from dirt and grime through the years and may be acting as a resistor, that's very common. I would look there first.

Have you cleaned the Jones plugs connecting the head to the cab? It's possible that's where your problem is. See the last page of the manual, 53-18 is the 10th connection down on the left side of the 24 plug. These can get corroded at times and cause issues. I'd do that quickly before getting into reflowing solder, etc.