Machine maintenance

So, I just acquired two ABM machines second hand. One seems to have had very little use and is smooth and *very* easy to operate. The other one, while it works well, is much harder to pull tight and the upper die seems “loose” (dunno how else to describe it!) I want to keep them working for as long as I’m making buttons (which I hope will be a loooong time) but can’t find anything about what I need to do to maintain these guys. So is there anything I need to do? Thanks!!