Disassemble the points by removing the contact breaker arm. This is held in position by a clip and spring. Note that the spring may easily be dropped on the floor – hence the need for a clean, well-lit work surface.
Loosen and remove the two screws which hold down the brass strip and which also clamp the low tension wire and the connection to the condenser. This brass strip is isolated from ground by insulating posts which should be inspected for cracks or other degradation. Note the order of construction of these components so that it can be rebuilt easily.
With the upper components removed, the base of the points housing can be unscrewed from the back plate and the capacitance of the condenser can be measured. The condenser rarely fails.
Reassembly is generally the reverse of the disassembly instructions above, but pay particular attention to the cleanliness of the contact breaker points. Even a thin film of oil from dirty feeler gauges can foul the points surfaces sufficiently to prevent a good spark.