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I am currently working on this old neglected 328-D Toro. Last night the hydraulic engaged without issue, would raise and lower the front deck. This morning after replacing the ignition switch I noticed the arm will no longer engage. Checking the hydraulic fluid level I saw it was pretty low. Topped it off and still nothing. Anybody have any advice on how I should proceed with trouble shooting this issue? Does this model have some kind of pump within the transmission case that pressurizes the system?