No power at key

yank the connector apart. If good, try to get a clip lead onto the ammeter posts, one at a time. Once again, you are measuring from the battery POSITIVE POST to first one, then the other, ammeter posts. - have not done this yet but should the wire come off the post before connecting the clip? it's very tight up there and will be difficult to place a clip...can I stab the wire near the post for a reading?

No need to disconnect at this time, and OK to stab into wherever you can make connection. Frankly, at this point it might make sense to pull out the cluster. On some cars it's easy to drop the column onto the seat for clearance. Just remove the bolts at the big floor flange, and the two or three clamping the column to the bottom of the dash, and it can sit on the seat. Now you'll have room to pull the dash out, and get to the back. Don't pull to hard on the PC board connectors. Do this, of course, with the battery ground unhooked. Wish I could get up there to help you.