Sometimes this can be a sign of bad tuning too, the power supply can be an issue. But I would also like to point out that some power supplies are more picky than others. A friend had a national power supply ( one of their nicest models ) and it ran all machines like a dream accept one from a friend of ours. His machine that he had built would do exactly the same thing you are describing. Turned out to be a reversed capacitor. Which was sending current back the wrong way and confusing the CPS circuit causing it to stop and start. Try it on an analog power supply. If it works fine then there is either or short somewhere or the cap could be reversed. Also the caps on the Micky Bee machines are not inline with the coils. You may want to wire it in like a standard machine.