727-904 REVERSE SLAMS HARD WHEN SELECTED

All I can speak of is my own. Hard engage of reverse only happens after it sits, and it sits for weeks at a time. The torque converter leaks down. The front pump in the trans doesn't run in park so refilling the torque converter wouldn't happen for a very long time. If I go straight from park to reverse I get a 1.5 second delay then bam, I've got reverse. Soooo I learned to first go straight from park to neutral, give it a few seconds to fill the converter, then to reverse. No bam.