usually harsh enguagement deals with the swash plate (wave spacer plate) in the clutch packs. If it breaks it doesn't cushion the clutch engagement and lets it slam into gear hard. Have seen this on many of them.

but check all your pressures and make sure they are good but you'll probably find it is some hardware problem internally.

And going on what edward said, sitting for long periods of time without use can cause its own set of issues.

try changing the fluid and filter (clean the sump screen) and see if that helps any