Mill looks a tad dry.
If it were me, I would grab some ISO32 Hydraulic oil from the local farm store if you can, it's cheap and does the job.
Slop it on all over and let it soak in. IMO, the oil suspends the dirt and grim better than spray lubes.
Thankfully you're not having to deal with rusted/seized up parts.
I would tear it down, remove the table and check out the GIBs. Clean, de-burr and lube.
That was the main problem with the one that sold around here back in July, it was dry. I knew the gent that bought it and he called me a couple of weeks later asking me to look at it. Got it tore down, and when I left he (and his son) were de-burring and stoning it.
Just my opinion, YMMV.
PS: post a picture of the drawbar when you get a chance to.