G'day Greenhead, there is no interlock on the sidestand on these scoots. You have gone through the checks pretty well and it does sound like the cdi, a common problem on this model. I bought a tzr 50 cdi for mine. It solved my problem although I had a bit of a headache trying to work out the wiring. I bought the one for the honda dio sa 50, it was $10, the kymco one was about $60, so the plug was different than my kymco. If you get one of these let me know and I will get the wiring colour codes for you.
cheers,
sid