The rear brake basically works but I've noted the foot lever appears a little floppy, like there's a return spring missing and I'm wondering if it's early signs of sticking in the slave cylinder? BTW, I've not been able to identify any return spring from the 2011 parts diagram.

Would a good hosing with WD40->Water->Lithium grease help...?

If you mean free play as in you can lift up the lever with no resistance mine was the same with no means of adjusting the amount of travel, so I used a tiewrap over a small piece of rubber on top of the lever which limited the travel against the frame, the master cylinder push rod could almost drop out of the master cylinder before I did this