Hi,
Sorry no one replied to your question,thing did get a bit slow with this site for a while.
What I would say is, do not use WD40 for lubrication,
Try something that has some PTFE in it.
Hi, in my last life when I worked we used a PTFE sheet to wrap around tubing to make it slide nicely, not sure where to get this now though, it was military grade stuff.
Bill