Are you using a screw-in fitting with your lube pump to fill the gear box? Is there a tube in the vent which reaches up into the gear box?
"There are two lube areas on the M2: The front of the impeller shaft (where the driveshaft and impeller shaft are connected via a set of bevel gears) and the rear of the impeller shaft (inside the stator). To do this job you’ll need a metric socket set, large flatblade screwdriver, 1/4 inch Allen wrench, two bottles of Mercury Premium Plus Gear Lube, Mercury lube hand pump, oil drain pan, wire brush, thread sealant, antiseize, and blue (medium strength) Loctite.
Adjust the trailer jack so the ride plate on the jetdrive is level.
Remove the center (fill/drain) plug in front of the intake grate. Use a large flatblade so you don’t ding up the screw. Don’t lose the little fiber washer underneath the screw.
Remove the off-center (vent) plug. The lube will begin draining. Inspect the lube for white streaks or foam (indicates water) or metal specks (indicates wear in the bevel gears). Let the lube drain into the pan while you begin working on the stator lube.
Disconnect the steering and thrust reverser cables.
Remove the four bolts holding the steering nozzle and thrust reverser to the jetdrive. Remove the assembly and set it aside.
Remove the four bolts holding the stator to the jetdrive. The stator will probably “stick” gently to the wear ring for now.
Return to the front lube area. Screw the pump hose into the center hole. Install the pump into the first bottle of lube. Begin pumping. You’ll use all of the first bottle and some of the second. Switch bottles when necessary. Eventually, the lube will start coming out of the off-center vent hole, which has a tube inside; when the lube is full it reaches the top of the tube and comes down through the vent hole.
Reinstall the off-center vent screw with its fiber washer and a dab of thread sealant on its threads. Unscrew the pump hose and reinstall the centered fill screw in the same way. The front lube is done.
Return to the stator area with the drain pan. Position the pan under the front of the stator. Pull STRAIGHT rearward on the stator to release it from the wear ring. If it sticks, tap gently with a rubber or plastic mallet. Continue pulling STRAIGHT back until the stator slides off the end of the impeller shaft. Lube will immediately begin draining. Set the stator face down on the drain pan to finish draining. Inspect the lube for white streaks or foam (indicates water).
It is important to remove and reinstall the stator straight along the impeller shaft so the impeller seal is not damaged.
Once the stator has drained, remove the center hex screw from the tip of the stator cone. Turn the stator over and let the remaining lube drain out. There’s always a little residual lube in there and this lets it all come out.
Inspect the impeller and wear ring for nicks, dings, and damage.
While the stator is draining, use the wire brush to clean the threads of all eight screws removed from the rear of the jetdrive.
Once the stator is completely drained, gently reinstall it on the back of the wear ring. Reinstall the associated screws using a dab of thread sealant, antiseize, or a very small amount of blue Loctite. Tighten in rotation and don’t overdo it; you’re tightening stainless steel bolts into aluminum threads. The service manual has torque specs but I just use my judgement.
Reinstall the center hex plug with a dab of thread sealant. Remove the top hex plug. Insert the lube pump hose (it won’t thread, you’ll have to hold it) and begin pumping. Fill until the lube reaches the bottom of the fill hole’s threads. Reinstall the top hex plug with a dab of thread sealant. The rear lube is done.
Reinstall the steering nozzle and thrust reverser assembly using a dab of thread sealant, antiseize, or a very small amount of blue Loctite. Again, tighten in rotation and don’t overdo it; you’re tightening stainless steel bolts into aluminum threads.
Reconnect the steering and thrust reverser cables. Confirm smooth operation of both from the driver’s seat. All done!
Time to complete: ~2 hours the first time, ~1 hour once you’ve done it before."
