Yep.... Heat is the #1 killer of transaxles. Those little cooling fans on top are always undersized and if you let mowing debris build up, clocks ticking on a failure. Both Hydrogear and Tuff Torq advise against pressure washing their units, so your alternative is compressed airSo the drive turned out to be almost out of fluid I took it off drained it cleaned it refilled it and bled it out and it’s working well at the moment. Fingers crossed it keeps running well. The entire drive was caked with dried up wet grass and oil that must have burped out of it from the heat. We cleaned it up and put the recommended 5w-50 (I think) synthetic oil in it. So far so good.
Going to do the bearing in the front wheels upgrade since the dang ole clip popped off and the wheel fell off. If it turns out to be a slick and long lasting mod eventually the other mower will get the same mod.