My dad has one of these, loves it to bits but unfortunately it keeps conking out on him whenever he goes away on it. Something to do with the regulator failing? He paid a bit extra for what was supposed to be a slightly better version than other aftermarket parts but it's lasted half the time. He's looking to sell it now, it's served him well for the past 10 or so years, 55K on the clock now
Can't speak for Blackbirds (apart from they're decent enough looking for a motorway missile), but regulator trouble can be really annoying when it happens because of several things that happen.
Regulators er.. regulate the voltage coming from the alternator (or generator (or magneto)) to the battery. They are there to keep the battery charged.
The alternator generates a huge range of amps and volts based on engine speed. The regulator is there to supply the battery and rest of the loom with around 11-13volts. The rest is meant to be be cooked off as heat.
When they fail they will cause a number of issues - mostly failure to charge the battery because of insufficient volts, or more annoyingly cooked (and dead) battery due to far too many volts. This also leads to blown fuses and other great symptoms.
The good news is that regulators themselves are fairly inexpensive and you could probably get an OEM one and plug and play the old one out for it.
Disclaimer: I am not a mechanic