Don't even try to replace with original .
Repair the old ones .
Pull out the adjusting plug and screw , get on the end of it with pliers and twist , it could be a bit tight but it's just pressed in .
Lay the batten on a bench ( or floor ) , with the broken bit and mark the total length .
Your going to need parts . NP battens for a long time come in two diameters, the smaller fitting perfectly inside the larger . And superglue.
Spare short NP battens are everywhere , your mates or shop , should get it for free , just need six inches of small and a foot of larger diameter per fix. Check that the smaller fits inside the the old batten and the new larger batten part .
Cut back the tip of the broken part of the batten so it is clean , it can splinter back a bit . One cm should do the trick . Smooth off with sandpaper.
With fine hacksaw cut 20 cm off the back of the broken batten .
Sand the edges of the six inch small batten piece .
Sand I the inside of the cut batten and the foot long piece of larger diameter .
Make sure the smaller tube slides nicely inside the larger .
Really quickly , ( and I mean really quickly ) , superglue half the length of the smaller diameter into the batten , breath !
Again really quickly glue the foot long piece over the sticking out smaller diameter.
Lay your new fixed longer batten over your measured lines . Chop the excess round end to length . Tap in adjuster plug and screw ,
Should be perfect length and better than new .

Ive done this many , many , times .