Lack of power (can't accelerate in third gear)

[Hanno Spoelstra]

Originally Posted by Lauren Child

What's involved in the advance mechanism? She's got an electronic ignition fitted by a previous owner, which should hopefully make a difference, but I've had *no* experience of ignition systems so that'll be something to learn.

I'm no expert either, but there is a mechanism which advances the ignition spark as the engine speed increases. If the mechanism does not work, the spark is not advanced resulting in a sluggish engine.
The electronic ignition cannot wander off like a mechanical one can, so it's probably not the cause of your problems - unless it's defective.

What happened / changed since it last ran fine?

H.