How long should a coil last?

[shed driver]

I've had some poor running and starting issues on my 1973 P5B Coupe. I replaced the coil 2 years ago when I fitted electronic ignition and it ran really well for a while. Since then the poor starting has returned and it seems there's low voltage on cranking which was going to be assessed by an electrician.

I had a spare coil in the garage, fitted it and the car fired up straight away. The electrician will eventually get round to fitting me in, but it may not be for a few weeks at least. Is there any harm running it with a (possible) fault to the feed? Also, how long should a coil last?

SD.

[shed driver]

Not at all, I got all the stuff as a single lot from a specialist.

Anecdotally there are quite a few classic owners who are mentioning branded coils, mainly Lucas are now made in China and seem to be failing prematurely.

SD.