as suggested, make sure it is gettting a full stroke on the valve spool. Probably so, if it is then go to the spool slice that controls the variable speed. Remove the relief valve - the one with the screwdriver slot plug facing the front of the combine. Take to a vice and you problably will have to apply a lITTlE heat to break locktite - it has a plastic poppet inside be careful - and turn the screw out to inspect poppet and spring - REMEMBER the n of turns it took to take out - reinstall and turn in 1.5 turns more. This should now give you about 100 more psi onthe cylinder. I have switched these with the reel speed plug in the field as they are the same and it helps sometimes.