I have an older 1995 Toro Groundsmaster 223-D mower that I use only on my personal property. Even though the mower has some age on it, it has been well taken care of and serviced regularly and is in quite good shape for its age with the exception of one problem. The problem, I think is in the hydro system. The mower act like the hydro fluid is low while I am driving on level ground or going down hill. It will pull for 20 to 30 feet and then it acts as if there isn't enough fluid for a second or two and then it will start pulling again for another 20 to 30 feet. This process continues as long as I am on level ground or going down an incline but NOT up hill. It does seem to run just a little bit better after the mower has run 30 to 45 minutes and gets good and hot. This problem has been going on for at least a year. The mower is operational and I can mow with it but it is starting to get on my nerves if you know what I mean. It doesn't do this at all when I am climbing UP a hill. It will climb just about any grade of hill with no problem whatsoever and it doesn't do this while driving in reverse either. Just going forward on level ground or down hill. The fluid and filter only have 17 hours on them. From my little experience with hydro drives, usually most problems occur when trying to go UP a hill...not down a hill. Any Ideas at all?????