Nice one, thanks for that suggestion! I’ll give that a go.

Ps. Nice name!

They are fuel overflow hoses. Attach a hose like shown on the other side and feed it underneath the bike away from any hot areas.

They're designed to flow gas away from the bike and hot areas should the bike fall over and the tap not be shut off.

@eric74 Fair play for getting on and replacing the tacho drive O-ring. Looking at your pics I'd say the oil is definitely coming from where the cable joins the tacho drive so I'd order the oil seal for this (item 7):

https://www.fowlersparts.co.uk/parts/4083282/dt125r-3py3-1991-999-a/tachometer-gear

Looking at the 4th image you posted up, the plastic breather stub should be right behind the tacho drive about where the old O-ring you mentioned is so it looks like your breather is missing (items 14 and 15):

https://www.fowlersparts.co.uk/parts/4083277/dt125r-3py3-1991-999-a/crankcase

Not sure whether oil would be visibly leaking out of here if it simply wasn't fitted (you never see any oil in the clear tube IIRC) so it may be that someone had the bright idea of plugging the hole with silicone sealant or something similar. Have a poke around here but be careful, if that's what's been done it would be too easy to end up with it disappearing into the crankcase, but if you're patient with the needle nose pliers/tweezers etc. you can remove a wodge of sealant like that from the outside.

It's doable. I've taken parts from 3 Mikuni 28s.One from my DT,one of a TDR250,one that has oil feed tube don't know what bike and made my current carb.
The one with broken is off,the bent tube is overflow if memory serves.
Chokes are the same.