The manual I just downloaded was for a ton of different Kanzaki transmissions. This is the text:
Transmission Oil Level Check screw it in. Pull out the dipstick and read the oil level on the dipstick. Check the transmission oil level on a weekly basis.
1. With the boat at rest in the water and the engine off, unscrew the dipstick (Figure 39, typical). Wipe it with clean rag or paper towel. Reinsert the dipstick, but do not screw it in. Pull out the dipstick and read the oil level on the dipstick.