Installing metal valve stems

[HalcyonDays]

Is there a trick to installing the metal valve stems on Model A tubes? I am 0 for two. I watched the video on You Tube and it appeared very straight forward. I installed the stems, checked for leaks then manually installed tube and tire on rim. Once installed leak happened between metal stem and tube. I did not apply any sealant as per video. Next step for me is to see if I can find tire shop to install tubes and tires on rim, perhaps they could do it with less stress on stem.



I was curious if anyone else ran into this issue and or if thy applied a little sealant.


Thanks for any suggestions.