I have a 54 NAA that was my grandfathers and then my fathers and now is mine. It runs great and I have been working cleaning it up and painting it as well as doing much needed maintenance. It has a snow plow and that is about all it has been used for in some time. When I lift the blade, it is choppy and bounces up. When I lowered it, it is smooth and no issues. What should I look at first as a possible issue? It has the old Vane pump and I have been told to consider a piston pump, but haven't seen if that conversion is bolt on or is there modification, welding, etc. Any help for a newbie would be greatly appreciated.