Actually, it's very easy to get out the shaft. Let me go through it, step by step:
1) find the motor
2) on the motor shaft, there is a piece that's bigger just before the shaft goes through the bottom of the boat
3) rotate the motor until you find the screws in that larger piece on the motor shaft
4) loosen the screw closest to the rear of the boat
5) pull out the drive shaft by the prop
Now that you have it out, give it a good coating of a water proof grease, preferably lithium based. Be sure not to get any on the area that goes into the bigger part on the motor shaft. In fact, you may want to leave the last couple of cm bare of grease
Once you have that completed, you can re-install the shaft. One other thing you COULD do, while the shaft is out, is to drill a small hole(maybe 2mm or slightly larger, if there isn't one already) through the side of the strut(the part just ahead of the prop and drive dog when the shaft is installed) so you can inject grease into it between runs
When you have the shaft back into the boat, you will need to tighten the screw that holds the shaft in. Before you do so, take it totally out, coat it with thread lock(orange or blue only, not red as red requires heat to get the screw out later)
When you're tightening the screw, make sure to leave a small gap between the strut and drive dog. This needs to be at least 2-3mm, so that the shaft won't bind when running. If it binds, remove the screw again, recoat with thread lock and reinstall, leaving a larger gap each time until it doesn't bind. You do need to be careful as if you go too far, the shaft won't have enough length left inside the coupler to hold it and you could lose the prop and shaft to the bottom of the pond. For example, on my sport 20 hydroplane, it has a .187 inch(4.75mm) shaft, similar to what your boat has except larger. To allow for it to "shrink" under load, I leave a 5mm space between the drive dog and the strut. This prevents the shaft from binding. I'll try to get a picture of it later today so you can look at it
Last edited by Hydro Junkie; 08-01-2020 at 04:26 AM.