I just saw your post whilst listening to Andreas Vollenweider !
If you get yourself a pin vice from say The Range, you can hold the stem and screw it on with a low risk of damage. Flatten the end of the stem with a fine abrasive stone and gently curve the edges of the end after cutting it very slightly too long.
I will gladly do it for you if you prefer.
Address on my website:
Webwatchmaker.co.uk.
Sent from my SM-G900F using Tapatalk