727 reverse failing.

how much fluid are you adding?
I carefully filled to the line on the dipstick when engine was warmed up but not running. I now know it should have being running whist it was being checked/filled.But that's how it was done. As the engine WAS running I put it through the gears with the handbrake on at standstill.
I checked the level again today without starting the vehicle and it's still 3" above top filling mark.