Not working or poor connection, but compare it to battery cranking voltage. For all I know, your battery is so dead or old that it is pulling down to 9 when cranking. You might see as much as 1/2--1 volt below battery with that test, but there should really not be "any."
That circuit comes off the ignition switch, through the bulkhead connector, and to the coil+ side of the ballast.
The ignition switch feed is starter relay stud---fuse link---through the bulkhead (big red ammeter wire)---to the ammeter--through the ammeter--out on the big black wire---to the welded splice---branch off to the ignition switch.
So you might have some voltage drop TO the ignition switch, you might have some drop INSIDE the ignition switch, and you might have some drop in the brown wire circuit.
Meanwhile, to see if this is most of or all of the problem, rig yourself a jumper wire direct from the battery (or starter relay stud) to the coil+. Don't leave this connected any longer than you need to test. With this in place, crank the engine and check the spark out of the coil wire with a test gap. You should get a nice snappy spark
