I think it's the hydro pump. The pump is a Tuff Torq Dup10e from Kanzaki. I've only found a couple for sale one from Kanzaki for $1900+ and one from Mulligans parts company for $1330. The mower only has 177 hrs. but was beat pretty hard. I got it from my brother as is. Does anyone know if these pan these pumps can be rebuild?