I just changed my regulator... Here's what I did...
Battery was flat and not charging:
1. Charged the battery on the Optimate
2. Tested the battery terminals - they were tight
3. Put the voltmeter across the battery - it measured 12.62V DC
4. Started the engine
5. Put the voltmeter across the battery - it measured 11.8V DC
6. Split the 77 connector
7. Put the voltmeter across the battery side - it measured 11.8V DC
8. Put the voltmeter across the regulator side - it measured 3.2V DC
9. Split the stator outlet connector
10. Put the voltmeter across each pin to each pin (each winding) - it measured 15.6V AC on each
11. Shut down the engine
12. Measured resistance across each winding - it measured 0.4 Ohms on each
13. Measured the resistance of each pin to ground - it was Open Loop on each
14. Replaced the regulator
15. Tested again - 12.49V not running and 13.87V running
As I was replacing the regulator, I:
i. Copaslipped the screws holding the regulator on
ii. Put liberal amounts of silicon grease inside the 77 connector - a known weakpoint
Then, just like a grandfather, I stripped the old regulator of anything that may come in use another day...
I made a little troubleshooting flowchart too...