Just got a good deal on an earlier model Sentar. It has one problem that I have found. When releasing the hand controls after going full forward, it pulls HARD to the left. It is tracking straight. I've made the neutral adjustments on both pumps, but it still pulls to the left when I release the controls. The guy I bought it from said he had the right pump replaced at the beginning of this season. A friend mentioned it may need to be bled. I have followed the manuals bleeding instructions, but I never see fluid coming out of the release valves. It seems like eventually fluid would follow the air out of these valves?? It also appears no air is coming out either. (Bubble test) Mower has 253 hours. 61", 25 hp. The pump oil looks very clean.