Purchased a used Gravely 148z (2005) last winter, mowed with it all summer (did very well), and then during early fall, I noticed there was a leak developing around the hydraulic filter (see picture). It was VERY slow, but it would be enough to pool up a little puddle about 3" on the cardboard in between mowing sessions (1 week usually). The hydraulic reservoir still reads within normal range, but I'm sure after plenty of mowing, it would drop. Since I didn't mow with it much afterward, I've put off servicing this. Is there a replaceable seal (aside from the one on the filter), or is it likely coming from some other source? There are no breaks in the lines running in or out of the filter, but from the looks of it, it appears the leaks is coming from somewhere above the filter housing. My next step would be to consult the dealer (80 miles away), but I thought I would check here as well for part/general information. Thanks for any information you can provide.