Power Steering Reservoir cap leak

Sorry if this has been asked but searching seems to bring up a lot of results for newer trucks... I am losing fluid fast from the reservoir cap, I'm pretty sure. I cleaned everything up and it is coating the reservoir all around. So the question is: am I looking at a new cap, or is there a larger problem? The truck is a 2000 Tundra, 4.7 4x4 extended cab (Access cab?) TRD. It just doesn't seem like there should be that much pressure coming back into the res... And nobody sells a cap, so... The gear was whining when the fluid went low, but it quieted right down with new fluid, until it leaked again.

No real steering issues that I can tell. I haven't had the truck long, and it's high mileage, but it turns easily, responds quickly, and doesn't seem to have much, if any, slop. Just looking for some ideas because the parts aren't cheap, res is a hundred bucks, pump more, rack even more... Thanks in advance.

 

It actually could be a result of air in system if it's done it enough even before you bought !

 

Best way to try and bleed power steering is to put it on Jack stands or soft surface (to prevent tire wear) and open the res cap and turn wheels back and forth for a little while.

 

It seems like air in the system was the problem. I flushed it, put a couple new hoses on, and it works like a champ now. Thanks!