Mercury Lower Unit - Gear Shift Issue

[Atyrautony]

To put this in context due to location in the world namely Kazakhstan, and availability of spares for old engines low we have just grafted a Mercury Lower unit onto a Force 115HP Power unit, this includes making a new gear change mechanism as the Force was a push actuate and the Mercury is a rotary. It all worked fine, until it appears that the cam on the gear rod has come off. I know this as I have suceeded in removing the shaft from the pocket. So to the question. As this is quite heavily modified I need to know if the front gear stays in the casing or does it come away on the output shaft when it is removed. Its a reasonable old Lower unit and I can take as many pictures as needed to help. Got some good guys arounf me but we need to know if we are going to have to undo the modifications we have meade to the power input shaft to get this thing apart.
TIA

 

[Chinewalker]

Remove rear bearing carrier, reverse gear, and propshaft. You can now see the pinion gear and forward gear. Remove nut from the pinion gear. Remove pinion gear. Now the forward gear should come out and give you access to the shift cam.

When you get it back together, make some provision to keep the shift rod in the unit. Normally the upper shift rod prevents the lower from riding up.

 

[Atyrautony]

So it the only thing that stops the selector shaft moving up the fact that it is connected to the upper shaft? Is there no circlip or a like holding it down in place?

 

[Chinewalker]

If there's a groove in the lower shift rod, below where the bottom side of the guide bushing resides, then yes, it would have a circlip. However, it isn't always enough to hold it in place, as I've had several slip out of the groove without much effort.