Alternator Issues? Flickering lights.

Hi, ive had my MGF for 9 years now and love it. Would never sell it, reliable, fun, cheap to run, love it. 

But, its developed an annoying thirst for alternators. For the first 4 years of ownership and about 40k miles it was fine on the original, then it failed, so fitted a new one, this lasted about a year (20k miles)  then overnight stopped working without warning. Annoying but at £90, "oh well" fitted another, again about a year (10k miles) later failed. Fitted another, this time a refurb from ebay, lasted about 2 years (10k miles, no longer full-time daily), failed. This time, though, with about a month of dim and flickering headlights and dash lights. Fitted a new cheepo one, this lasted about 2 months. Fitted a new hella unit, after about a month the flickering lights started again, and then it fell to bits (3 blades came off the fan internally. So I got another new one on warranty, this has done about 8 months, but far less regular use possibly just 1k miles, and its now intermittently having 10 min stints of flickering headlights and dash lights. Generally it runs at about 13.1Volts, with lights on its 12.7. Final bit of rambling history, the last 2 to die and this one have made a bad smell (plastic-ie electrical death!) off and on for the final months. 

So my questions are:
- What can be killing them! (cheep, original and expensive-ish are all failing)
- Flickering etc can be (on my old MGBs) voltage regulators... but they are (i think) inbuilt to the alternator on modern cars like the F (relative....) arnt they?

FYI, car is a 1998 MGF VVC with AC. Also worth mentioning the thick cast aluminium bracket that hold the alternator on underneath it is snapped (good effort by a garage I used before saying screw this I'm doing it all myself) but as its a rough finish and a jagged snap, once positioned in place holds just fine. The belt doesn't squeal, all is secure by the other bolt on top keeping level and the other half of the bracket under keeping it down.

Thanks, James.

Given you have tried different makes of alternator which have all failed it would be worth looking at the common factor as a possible cause. The damaged alternator bracket could be causing excessive vibration sufficient to harm the alternator but not enough for yout to necessarily hear or feel whilst driving. I would reccommend ringing around the specialist breakers favoured by many on the forum for a good 2nd hand bracket. It will probably take you an hour to fit, wont cost much and will obviate a likely cause.

I agree about replacing that bracket. It might look like it fits together but in reality it is being held on by one bolt and not the strongest of the two to the block.
Alternators are basic but delicate items and the vibrations could be shaking it apart..even though you don't feel it.

My auto electrician mate says the buggered bracket is the most likely cause actually his words were "change the bloody bracket! he's never one to mince words, and is even more direct than I am!
 

If, if the main ground return is via the bracket & it’s broken, then the high currents required to run hungry services, such as headlights will be deriving their return via a secondary route.
Obviously when diagnostics are done at a distance, the diagnoser is at a great disadvantage. I would say all of our regular contributors would be reaching for their meters & would be going around probing for problems , however the low voltage & current of a normal test meter, expressly a digital model, wouldn’t show an return problem.
I recall a ground return being so poor that the choke cable was providing the return for the engine, so bad was the “official” grounding points.
On the meter everything showed up as good, it was only when the starter motor was drawing maximum current did the choke cable light up like a heating element. That was fun!
M