Finally collected my side openers.
They were a little damaged, and completely filthy. The locking mechs on both windows were partially seized and made opening them difficult, which is why I think they had started to break.
I took them apart, glued the runners back down with some grip and grab I got from my Fiance's Grandad (Amazing stuff!), and then WD40'd the locking mechs.
Gave them a good clean, and put them back together. Sprayed loads of silicone spray into the runners, and they are like new now. Will be cutting them in on Wednesday.
Trial fitted the new arches too. They fit SOOO much better than the old ones, and look right on the van.
Fronts will take a bit of trimming because they will foul the bottom of the doors, but I can work with that
And there we have it. Transit Connect arches do give a good bit extra arch width, for anyone wondering weather the are worth paying out for.