When I put an Impact apple and base in an Imex/Taigen Tiger One I had cupola issues, and this little video excerpt shows what I did to fix the problem. I use white tack (or blue tack) to hold down the cupola of choice and haven't lost one yet. I also set up the base so I can pop out two screws and rotate 45 degrees to change to TFA.

https://www.youtube.com/watch?v=_x0RmjXILc8 If I were to do it again the only thing I'd do differently would be to use plastic cupolas instead of metal.

https://www.aliexpress.com/store/pro...612.0.0.6tMo6i

In plastic I can get three cupolas delivered to Detroit for $13 US and yes, that's shipping included. I've used Heng Long's Store several times and haven't had a single problem yet. Your experience may vary, in case any of you jokers are lawyers.