Im going to look at a used lesco skid sprayer 5.5 kawi with the hypro pump. Im just going to assume that the pump needs to be rebuilt right off the start even though the owner claims it works like a charm. What specific things should i look for? Fill it all the way up wait a period of time and check for leaks? Operate hose reel and make sure it works just fine. What typically goes out on these units? This particular unit was bolted inside of a van that was traded in to a car dealership. Dealership is trying to get what they can out of the unit. Any help is greatly appreciated.