I just did some quick research and seems that if you want to tighten the slop for forward and reverse the adjustment would be at the transmission. This isn’t for a Moomba but I imagine the principle/mechanics are the same:
https://uploads.tapatalk-cdn.com/202...41ec407553.jpg
Watching this video leads me to believe that if you needed to adjust either forward OR reverse then that could be done at the shifter by adjusting the brass piece that slips into the hole on the shift lever (threading it further in our out).
https://youtu.be/9KNzQxpAeE4