Classic/Antique Car Repair: 79 MG midget, roadster factory, moss motors

Question
I purchased this fine '79 MG midget few months ago, running GREAT! starting right up with just a twist of the key. I've put around 250 miles on it since with maybe about 25 miles on the longest stretch, here's the problem.... I've noticed getting harder to start, and idle rough, so I replaced the plugs (gapping at 25) this made some improvement but down hill since. The car will not even start now however motor turns over fine, all electrical appears fine, belts and fuel lines okay. Thinking electrical I replaced the orig. ignition coil(new) still no start. I'm still thinking electrical I open the distributor and "WHAT the heck"? I've never noticed it before but my distributor has a box connected to it (EID unit) along with wires connected to a CEI amplifier, after further inspection I see what appears to be that someone has done away with the EID system and then I see what I think might be my whole problem, there's an circular disc just below the rotor that has cracked and crumbled from age, or what ever? where do I get one of these and what is it called? This disc looks as thought it may have had some slots cut into it so the CEI amp. eye could read in between them? If I'm wrong on this what else could have strangle the motor so quick? any suggestions what else I need to check or have tested would be great.
More info on the car..
1500 CC all orig. from what I can tell, Stromberg carb, etc. Appears most of the emission has been removed. I do know that it's a FED. and not a CAL. engine.
By the way, I think you are very knowledgeable on midgets and I respect ALL your suggestions and comments.
Thanks,
David

Answer
Hi David,
A disk with slits in it is the trigger for the ignition and if it is damaged, the engine can not run. The 79 Midget 1500 is a Triumph Spitfire engine and there are parts available for it from many sources. There were several aftermarket ignition systems available. Put "Moss Motors", "The Roadster Factory" and "Victoria British" in Google or Yahoo search engine for a replacement part or alternate ignition system. Also, you should contact your local British car club and you may find all you need locally. Some auto parts stores still list a aftermarket ignition system for the 1500 Midget / Spitfire.
If you can't find anything let me know.
Howard