Hyundai R16-9 Mini Excavator 1.6 Acting Up

Hello. I own a Hyundai R16-6 excavator and yesterday while using it in the heat after a few hours my tracking in both directions went very weak on me, to the point that I could not crawl up a slight grade or have independent control of the tracks. I've owned the machine for a couple years now and it has about 1100 hours. I restarted it this evening and it seems like the major tracking problem was gone. Since day one I've noticed that the hydraulic pump (or something internal) will make a bit of whining noise of and on. Not terrible, but audible enough to notice. I changed the hydraulic fluid filter that is in the reservoir last year and it seems good on fluid level, checking it in the prescribed position. Any ideas what would a possible heat related condition would highlight? I'm thinking of finally taking it into the authorized dealer / shop to evaluate, but hate to find it was something a novice like myself wasn't aware of....like switch to a different fluid or drain and fill with fresh fluid on a regular basis. I'm no equipment expert, but seems to always have tracked a little hokey between the two track levers, typically requiring some sort of engagement to both sides in order to bias in direction or the other. Thanks for any help / ideas you guys can lend. My apologies for the novel.