I have a L402 Hydraulic issue,Issue is that there is zero action from any of the controls either the front bucket or the 3 point linkage,this is intermittent ie hydraulics work fine then after tractor sits for a few days the hyd dont work then next time i start it it is fine,appears there is a sticking valve somewhere can someone please point me in the right direction to find this valve or possibly a link to the hyd schematic.thanks in advance.