UPDATE
I’ve read and re read all your very welcome and appreciated comments and taken the plunge. I’ve removed the slide, disassembled same, removed all swarf and gunge, cleaned with wd40, rubbed down with fine steel wool and wiped clean. I applied lubrication oil and then reassembled. It’s now approximately the same ‘stiffness’ as the cross slide and I’ve even managed to remove the ‘play’.
Thanks very much everyone, I’m over the moon and my lathe still works 😀
Kev