Re: Lift arm position lever and control valve questions L3010
I have a L3010 with a BL4690L (3pt hitch mount) backhoe. You are correct that the tractor's 3pt hitch "position control" lever does need to be in the forward or down position. Otherwise, if left in the up position, this will attempt to drive the rear lower lift arms up against the backhoe mounts and cause the hydraulics to "overload". This causes the front end loader to act exactly like you describe (not going down consistantly). This will happen on mine everytime! Obviously, this is not good for the hydraulic system.
As far as the "control valve adjustment" under the seat, I'm assuming your referring to the "3 pt hitch lowering speed" knob. I don't know if it could effect your FEL bucket speed or not, as I would guess your "position control" lever is your issue.
I included a quick scan of my manual's "Hydraulic Unit" pages for your reference.
Hope it all helps...