Took one of the plugs out, set it against the head and turned it over... there just no spark at all.

I have replaced the distributor cap, rotor arm and the ignition coil. Checked all the plugs and leads. Checked all the fuses. Checked the earths. Cleaned out the carb (pierburg 2e2).
The only thing I can think of it being is the distributor... Now I know that Polos give problems with the Hall sender. Could it be this?
Is there anything else I have overlooked? Has this happened to anyone else?
Any help appreciated