Moved my md75 out of storage plow went up, will not go back down. I ran through the troubleshooter I confirmed the solenoid is getting power. Swapped tow coils no change. Removed the valve & cleaned it no change. I unhooked the lift pistons hose still will not go down with out ALOT of force. I’m assuming there is some swelling inside the piston. Should I just replace or try & use a lube/ penetrant to see if I can get to move up & down. Opinions?