Now I think we are getting somewhere?
Rather than talking about tinning the wire we should be talking about soldering irons, and quality solder.
Solder must be the main issue here.
If you are trying to use lead free solder then you need to stop, and buy some good old Kester 44.
Because soldering a 42 awg poly wire to an eyelet should be very easy.
Thanks for you pictures.
Looks like you're enjoying your hobby!