I would say your Victa has a marginal ignition coil. It happens over here to the Lawn-Boy coils all the time. Very frustrating because sometimes they work ok. It is possible that you need a new spark plug too. In fact I would start with a new plug and go from there. I have had a mower that did the old "work sometimes and not others thing" to me over a period of a year before I finally changed the ignition coil assembly and the mower has run like new ever since. With a new ignition coil and plug you might be amazed at how much easier the mower is to start. By the way it may be that your ignition is in separate pieces as opposed to a single unit like Lawn-Boy. So check with the dealer before you get parts. You may need a pick-up coil and or an ignition coil etc. Depends how they made them.

Being British, I hope you don't see the name "Lucas" on any of the parts. Horrors!

baymee, Do you know why the British drink warm beer?............Lucas refrigerators.......
OK, Yea I know that's an old joke.

I drove my 1963 Triumph motorcycle for 35 years.