qualcast 43s suffolk punch. no spark?

can you advise, I have had my above described mower running, but then it stopped, NO SPARK. I have had the wipac ignition module tested, at a mower service shop and found to be in order. there are no points fitted on these models. I have tried a different flywheel magneto, but still there is no spark. also tried, new spark plug, and plug cap with no sign of a spark, where can I now look, without buying a new mower? Thanks in anticipation.