I bought a slightly used Ryan aerator IV last year. It probably has 100 - 5,000 sf jobs on it. Had it serviced three times. However, I have noticed that it just does not have the same pull as it did last year. I feel that I am doing too much pushing and the machine is not doing enough pulling on its own. It has a 5hp engine. Would like some feedback before I mention this problem to the service guy. Thanks in advance.